Pyroelectric lens system and detection method of target detection object

Abstract

The embodiment of the invention provides a pyroelectric lens system and a detection method of a target detection object. The pyroelectric lens system includes a lens, at least two PIRs, and a processing module. Wherein the base line of the cross section of the lens is arc-shaped, and the at least two PIRs are parallel to each other and are arranged on the same plane of the concave surface side of the lens. Each PIR comprises at least two induction elements, the at least two induction elements are arranged in parallel, and the connecting line of the at least two induction elements is parallel to the connecting line of the at least two PIRs. The processing module is used for adjusting the distance between the adjacent PIRs so as to detect the target detection object, and the distance between the adjacent PIRs is in direct proportion to the speed of the target detection object. The system achieves the effects of improving the accuracy and flexibility of detection and reducing the cost and the overall size of the system.

Description

Technical Field

[0001] The present application relates to the field of lens technology, and in particular to a pyroelectric lens system and a method for detecting a target object. Background Art

[0002] In order to improve the battery life of surveillance cameras, surveillance cameras are usually required to be awakened under certain conditions and to capture or record targets. The more common method in the industry is to use a passive infrared detector (PIR) solution to detect target objects, so as to trigger the wake-up and capture functions of the surveillance camera when the target object is detected.

[0003] In the existing PIR solution, the single lens + PIR structure is difficult to meet the detection requirements of target detection objects with different speeds. At present, the switching of different PIR + lens combinations is mainly achieved through single device with multiple windows or single window with multiple devices according to the actual scene requirements.

[0004] However, the existing technologies have low detection accuracy and flexibility, large size and high cost. Summary of the invention

[0005] The embodiments of the present application provide a pyroelectric lens system and a method for detecting a target object, so as to improve detection accuracy and flexibility and reduce the volume and cost of the pyroelectric lens system.

[0006] In a first aspect, an embodiment of the present application provides a pyroelectric lens system, comprising:

[0007] A lens, at least two PIRs, and a processing module;

[0008] The cross-sectional baseline of the lens is in an arc shape, and the at least two PIRs are parallel to each other and are arranged on the same plane on the concave side of the lens;

[0009] Each PIR comprises at least two sensing elements, the at least two sensing elements are arranged in parallel, and a line connecting the at least two sensing elements is parallel to a line connecting the at least two PIRs;

[0010] The processing module is used to adjust the distance between adjacent PIRs to detect the target object, and the distance between adjacent PIRs is proportional to the speed of the target object.

[0011] In a second aspect, an embodiment of the present application provides a method for detecting a target object, which is applied to a processing module in the pyroelectric lens system described in the first aspect, and the method includes:

[0012] Determine the target distance according to the speed of the target detection object and a preset mapping relationship, wherein the speed of the target detection object is obtained in response to an adjustment operation of the user or is acquired according to a speed sensor, and the preset mapping relationship includes a corresponding relationship between the speed and the distance, and the target distance is proportional to the speed of the target detection object;

[0013] According to the target distance, adjusting the distance between adjacent passive infrared detectors PIR in the pyroelectric lens system;

[0014] The target object is detected by the pyroelectric lens system.

[0015] The pyroelectric lens system and the detection method of the target detection object provided by the embodiment of the present application, the pyroelectric lens system includes a lens, at least two PIRs and a processing module. Among them, the cross-sectional baseline of the lens is arc-shaped, at least two PIRs are parallel to each other, and are deployed on the same plane on the concave side of the lens. Each PIR includes at least two sensing elements, at least two sensing elements are arranged in parallel, and the connection line of at least two sensing elements is parallel to the connection line of at least two PIRs. The processing module is used to adjust the distance between adjacent PIRs to detect the target detection object, and the distance between adjacent PIRs is proportional to the speed of the target detection object. In this technical solution, the detection requirements for detection objects of different speeds can be met by adjusting the distance between adjacent PIRs, thereby improving the accuracy and flexibility of the detection. In addition, the system only needs one lens + at least two PIRs to be implemented, with low cost, and at least two PIRs are on the concave side of the lens, reducing the overall volume of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0017] Figure 1 This is a schematic diagram of the scenario of using the PIR solution to realize the trigger wake-up and snapshot functions of the camera;

[0018] Figure 2 Schematic diagrams of lenses corresponding to high-speed detection objects and low-speed detection objects respectively;

[0019] Figure 3 Schematic diagram of the structure of the pyroelectric lens system provided in this application Figure 1 ;

[0020] Figure 4 A schematic diagram of the lens viewing area provided in an embodiment of the present application;

[0021] Figure 5 A schematic diagram of the core position of a single-layer viewing area provided in an embodiment of the present application;

[0022] Figure 6 A schematic diagram of the propagation principle of infrared rays provided in an embodiment of the present application;

[0023] Figure 7 Schematic diagram of bright area distribution in the highest speed scenario provided in the embodiment of the present application Figure 1 ;

[0024] Figure 8 A schematic diagram of the angles between adjacent viewing areas provided in an embodiment of the present application;

[0025] Fig. 9 A schematic diagram of the relationship between PIR responsivity and frequency provided in an embodiment of the present application;

[0026] Fig.10 A schematic diagram of bright area distribution in the lowest speed scenario provided in an embodiment of the present application;

[0027] Fig.11 It is a schematic diagram of the structure of 2 PIR+lenses in the prior art;

[0028] Fig.12 A schematic diagram of edge incidence angle provided for an embodiment of the present application;

[0029] Fig.13 A schematic diagram of the position of the opaque baffle provided in an embodiment of the present application;

[0030] Fig.14 Schematic diagram of the structure of the pyroelectric lens system provided in the embodiment of the present application Figure 2 ;

[0031] Fig.15 A schematic diagram of the structure of the PIR+filter provided in the embodiment of the present application;

[0032] Fig.16 A schematic diagram of the spatial coordinates of the pyroelectric lens system provided in an embodiment of the present application;

[0033] Fig.17 A schematic diagram of the inner wall of a lens provided in an embodiment of the present application;

[0034] Fig.18 A three-dimensional schematic diagram of a pyroelectric lens system provided in an embodiment of the present application;

[0035] Fig.19 A schematic diagram of a process for detecting a target object provided in an embodiment of the present application;

[0036] Fig. 20 A schematic diagram of electrical signals in the highest speed scenario provided in an embodiment of the present application;

[0037] Fig.21Schematic diagram of bright area distribution in the highest speed scenario provided in the embodiment of the present application Figure 2 ;

[0038] Fig. 22 A schematic diagram of electrical signals in the lowest speed scenario provided in an embodiment of the present application;

[0039] Fig.23 An electrical signal generated for a low-speed detection object in the highest-speed scenario provided by an embodiment of the present application;

[0040] Fig.24 An electrical signal generated for a low-speed detection object in the lowest speed scenario provided in an embodiment of the present application.

[0041] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0042] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0043] First, the terms used in this application are explained:

[0044] PIR: Detects infrared radiation emitted by the human body or other objects based on the pyroelectric effect.

[0045] Sensing element: Pyroelectric sensor. When the infrared radiation emitted by the human body or other objects with a temperature higher than the environment shines on the pyroelectric material of the sensing element, the pyroelectric material absorbs the infrared energy, the temperature rises, and an electric charge is generated on the surface, causing the sensing element to form an electrical signal output, thereby achieving target detection.

[0046] Lens: It is used to collect infrared radiation from a larger range of space and focus it onto the sensing element inside the PIR, achieving the functions of focusing and collecting and converging the radiation energy of the heat source.

[0047] Viewing area: The spatial area where PIR can sense infrared radiation emitted by the human body or other heat sources is determined by the installation position and angle of the lens and PIR. The lens focuses infrared radiation from different directions onto the sensing element. Each local lens is connected to the PIR to form a specific viewing direction. The sensing element matches to achieve the viewing area range in this viewing direction. The viewing area ranges of multiple viewing directions are combined to form the viewing area range of the entire PIR.

[0048] Bright area: The area within the PIR field of view where the PIR can effectively sense and detect changes in infrared radiation from the human body or other heat sources. In this area, when a target object moves, the detector can more sensitively receive changes in infrared radiation.

[0049] Dark area: The area within the PIR's field of view where the PIR is not sensitive to or cannot effectively detect changes in infrared radiation from the human body or other heat sources. In a dark area, even if a target object moves, the PIR cannot accurately receive enough infrared radiation changes, and thus will not trigger the normal response mechanism.

[0050] Frequency: The density of intervals between light and dark areas.

[0051] Next, the background of this application is explained:

[0052] Existing surveillance cameras, due to the difficulty of wiring in the environment, generally use batteries + solar energy to power the surveillance cameras. In order to improve the endurance of surveillance cameras, surveillance cameras are usually required to be awakened under certain conditions and to capture or record targets. In some scenarios, such as identifying intrusions or detecting wild animals, the more common method in the industry is to use PIR solutions to detect target objects, so as to trigger the wake-up and capture functions of the surveillance camera when the target object is detected.

[0053] Figure 1 The following is a schematic diagram of the scenario using the PIR solution to realize the camera's trigger wake-up and snapshot functions. Figure 1 As shown in part (a) of FIG. 1 , the scene includes a lens and a PIR, and the PIR includes two sensing elements, namely, sensing element 1 and sensing element 2. The arrow direction is the direction in which the person moves forward, and sensing element 1 and the lens form a bright area 1, and sensing element 2 and the lens form a bright area 2.

[0054] pass Figure 1It can be seen more intuitively in part (b) that when the person moves in the direction of the arrow, he will pass through two bright areas respectively. When the person is in bright area 1, the infrared radiation of the person will irradiate the sensing element 1, so that the sensing element 1 forms an electrical signal output; similarly, when the person is in bright area 2, the infrared radiation of the person will irradiate the sensing element 2, so that the sensing element 2 forms an electrical signal output; when the person is between the two bright areas, no electrical signal is generated.

[0055] It should be understood that the electrical signal in this scenario can refer to Figure 1 The curve in part (c) is shown.

[0056] Further, according to the electrical signal generated by the PIR, it is determined whether the electrical signal characteristics of the target detection object are met. If the characteristics are met, the monitoring camera is controlled to turn on and take pictures.

[0057] In practical applications, the lens will be divided into multiple partitions to form multiple local lenses. The partitions of the lens need to be designed according to the movement characteristics of the target detection object. For example, when the target detection object moves at a high speed, the lens needs to have a wider partition so that it can quickly capture the infrared radiation emitted by the high-speed moving target detection object; when the target detection object moves at a low speed, a narrower partition needs to be formed to improve the collection efficiency of the infrared radiation of the target detection object.

[0058] Figure 2 Schematic diagrams of lenses corresponding to high-speed detection objects and low-speed detection objects. Figure 2 As shown in the figure, the rectangles are the partitions of the lens, and the circles are the core positions of each local lens. It can be clearly seen that the width of the lens partition designed for low-speed detection objects is narrower than that of the lens partition designed for high-speed detection objects. Under the same lens size, the number of lens partitions designed for low-speed detection objects is greater than the number of lens partitions designed for high-speed detection objects. When there are too many partitions, the area of ​​a single partition is small, and the long-distance detection capability is weak.

[0059] According to the above characteristics, for target detection objects of different speeds, the single lens + PIR structure has the problem of low detection accuracy. Specifically, in the lens + PIR scenario designed for high-speed detection objects, if there are low-speed detection objects, the blind area is large and the detection area is small, which may cause the problem of easy missed detection; in the lens + PIR scenario designed for low-speed detection objects, if there are high-speed detection objects, there are many partitions, the frequency of cutting bright areas is too high, and the responsiveness and electrical signals generated by high-speed detection objects are low.

[0060] In order to solve the above problems, the existing technologies are mostly implemented through a single device with multiple windows, or a single window with multiple devices. Specifically, a single device with multiple windows refers to deploying two groups of PIR+ lenses on a device (such as a surveillance camera), one group for realizing the detection of high-speed detection objects, and one group for realizing the detection of low-speed detection objects. In actual applications, the two groups of PIR+ lenses are switched according to the actual scene requirements. Single window with multiple devices means that one group of PIR+ lens structures are deployed on two devices respectively, so that one device realizes the detection of high-speed detection objects and the other device realizes the detection of low-speed detection objects. Similarly, in actual applications, the two devices are switched according to the actual scene requirements.

[0061] However, in practical applications, the prior art has the following technical problems:

[0062] 1. There are only two fixed states (high-speed state and low-speed state) for users to switch, and the detection accuracy and flexibility are low.

[0063] 2. Regardless of whether it is a single device with multiple windows or a single window with multiple devices, the system used to implement the detection will be very large and the cost will be very high.

[0064] In summary, the existing technology has low detection accuracy and flexibility, large size and high cost.

[0065] Based on the above technical problems, the technical concept of the present application is as follows: for low-speed detection objects, it is not easy to detect when the dark area is large. Therefore, compared with high-speed detection objects, low-speed detection objects require more bright areas. Considering that the bright area within the field of view of the PIR is jointly determined by the installation position and angle of both the lens and the PIR, a PIR+lens structure can be designed, which includes at least two PIRs. By changing the distance between adjacent PIRs in the at least two PIRs, the position of the bright area formed by each PIR is changed, thereby changing the range of the bright area within the field of view of the PIR. In this way, it is possible to achieve accurate detection of target detection objects of different speeds through a PIR+lens structure, the overall volume of the system is small, the cost is low, and the accuracy and flexibility of detection are high.

[0066] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0067] Figure 3 Schematic diagram of the structure of the pyroelectric lens system provided in this application Figure 1 .like Figure 3As shown, the pyroelectric lens system includes a lens, at least two PIRs ( Figure 3 Two PIRs (PIR1 and PIR2) are taken as an example for illustration. In actual applications, the number of PIRs may be other number greater than 2) and a processing module.

[0068] It should be understood that the cross-sectional baseline of the lens is in an arc shape, the concave surface of the lens faces the PIR direction, and the convex surface faces the target detection object direction. The at least two PIRs are parallel to each other and are deployed on the same plane on the concave side of the lens.

[0069] It should be understood that the target detection object can be a person, an animal or other heat source that can emit infrared radiation, which can be determined based on actual conditions, and the embodiments of the present application do not impose specific limitations on this.

[0070] Optionally, at least two PIRs are deployed in a single-board separated form, and the distance between adjacent PIRs is adjustable.

[0071] Optionally, at least two PIRs are deployed in a symmetrical and centered state with the central axis of the lens as the symmetry center.

[0072] Each PIR includes at least two sensing elements, and the at least two sensing elements are arranged in parallel. Moreover, the arrangement direction of the at least two PIRs is consistent with the arrangement direction of at least two sensing elements in each sensing element, that is, the connection line of the at least two sensing elements is parallel to the connection line of the at least two PIRs.

[0073] The processing module can be connected to at least two PIRs by wire or wirelessly to adjust the distance between adjacent PIRs in the at least two PIRs to detect the target object.

[0074] In one possible implementation, when decreasing the distance between adjacent PIRs, the PIRs may be controlled to move toward the central axis of the lens until the distance between adjacent PIRs reaches the target distance; when increasing the distance between adjacent PIRs, the PIRs may be controlled to move away from the central axis of the lens until the distance between adjacent PIRs reaches the target distance.

[0075] It should be understood that the target distance can be determined according to the speed of the target detection object and the preset mapping relationship. Among them, the distance between adjacent PIRs is proportional to the speed of the target detection object. It should be understood that an adjustable distance range is pre-set in the processing module. When the distance between adjacent PIRs is at the adjustable maximum distance of the adjustable distance range, the bright area formed by the pyroelectric lens system is the smallest. As the distance between adjacent PIRs gradually decreases until it is at the adjustable minimum distance of the adjustable distance range, the bright area formed by the pyroelectric lens system is the largest to meet the detection requirements of low-speed detection objects.

[0076] It should be understood that the bright areas corresponding to different distances between adjacent PIRs will be Figure 7 as well as Fig.10 The embodiments shown are specifically explained and will not be described again here.

[0077] Optionally, the processing module may also be pre-set with a preset mapping relationship, where the preset mapping relationship includes a corresponding relationship between speed and distance.

[0078] In a possible implementation, the pyroelectric lens system further includes a speed adjustment knob. The user can determine the speed of the target detection object according to the actual scenario and adjust the speed adjustment knob. Accordingly, the processing module responds to the user's adjustment operation, obtains the speed of the target detection object input by the user, and then searches for the target distance corresponding to the speed of the target detection object in the preset mapping relationship, and adjusts the distance between adjacent PIRs according to the target distance.

[0079] In another possible implementation, the pyroelectric lens system further includes a speed detection sensor, which is used to determine the speed of the target detection object and send it to the processing module. Similar to the above implementation, the processing module is used to adjust the distance between adjacent PIRs according to the speed of the target detection object and a preset mapping relationship. That is, according to the speed of the target detection object detected by the speed detection sensor, a search is performed in the preset mapping relationship to determine the target distance corresponding to the speed of the target detection object, and the distance between adjacent PIRs is adjusted according to the target distance.

[0080] In this implementation, the distance between adjacent PIRs in the pyroelectric lens system can be adjusted in real time according to the speed of the target detection object in the actual scene, so that the pyroelectric lens system can meet the detection requirements of detection objects at different speeds, thereby improving detection flexibility and accuracy.

[0081] The pyroelectric lens system provided in the embodiment of the present application includes a lens, at least two PIRs and a processing module. Among them, the cross-sectional baseline of the lens is arc-shaped, at least two PIRs are parallel to each other, and are deployed on the same plane on the concave side of the lens. Each PIR includes at least two sensing elements, at least two sensing elements are arranged in parallel, and the connection line of at least two sensing elements is parallel to the connection line of at least two PIRs. The processing module is used to adjust the distance between adjacent PIRs to detect the target detection object, and the distance between adjacent PIRs is proportional to the speed of the target detection object. In this technical solution, the detection requirements for detection objects of different speeds can be met by adjusting the distance between adjacent PIRs, thereby improving the accuracy and flexibility of the detection. In addition, the system only needs one lens + at least two PIRs to be implemented, with low cost, and at least two PIRs are on the concave side of the lens, reducing the overall volume of the system.

[0082] Optionally, for any adjacent PIRs, when the distance between the adjacent PIRs is the maximum adjustable distance, the pyroelectric lens system is used to detect the set highest speed detection object. The line connecting the first PIR in the adjacent PIRs and the first partition of the lens is parallel to the line connecting the second PIR in the adjacent PIRs and the second partition of the lens; the first partition and the second partition are adjacent partitions in the lens, and the relative position relationship between the first partition and the second partition is the same as the relative position relationship between the first PIR and the second PIR.

[0083] It should be understood that the relative position relationship between the first partition and the second partition is the same as the relative position relationship between the first PIR and the second PIR, which means that if the first partition is on the left side of the second partition, the first PIR is also on the left side of the second PIR; if the first partition is on the right side of the second partition, the first PIR is also on the right side of the second PIR.

[0084] In practical applications, the lens may include a single-layer viewing zone or a multi-layer viewing zone. Figure 4 This is a schematic diagram of the lens viewing area provided in the embodiment of the present application. Figure 4 As shown, the lens includes a double-layer viewing area, the upper viewing area corresponds to a long distance, and the lower viewing area corresponds to a short distance, so that the target detection object can be detected at both a long distance and a short distance.

[0085] For each layer of viewing area, the principle of a separate core area in the center and symmetry of the sides is met. This principle will be achieved through Figure 5 The illustrated embodiment is specifically explained and illustrated, which will not be described in detail here.

[0086] Optionally, based on product requirements, a protruding structure can be defined on the long axis side of the lens to prevent the lens from being installed 180 degrees in the reverse direction.

[0087] It should be understood that adjacent partitions refer to adjacent partitions at the same layer.

[0088] Further, Figure 5 The illustrated embodiment further explains each partition.

[0089] Figure 5 This is a schematic diagram of the core position of a single-layer viewing area provided in an embodiment of the present application. Figure 5 As shown, the lens includes 7 partitions, and the corresponding core positions are core 1, core 2, core 3, core 4, core 2', core 3', and core 4'. Among them, core 1 is on the central axis of the lens, core 2 and core 2' are symmetrically arranged with the central axis of the lens as the symmetry center; core 3 and core 3' are symmetrically arranged with the central axis of the lens as the symmetry center; core 4 and core 4' are symmetrically arranged with the central axis of the lens as the symmetry center.

[0090] Reference Figure 5 As shown, a pyroelectric lens system including two PIRs is taken as an example. Assuming that the core position of core 1 is (0, f), and the distance between the first PIR and the second PIR is d1, the coordinates of the first PIR are (-d1 / 2, 0), and the coordinates of the second PIR are (d1 / 2, 0). The angle between the line connecting the center point of the first PIR and core 1 (the core position of the first partition) and the Y axis is θ1, and the angle between the line connecting the center point of the first PIR and the position of core 2 (the core position of the second partition) and the Y axis is also θ1, that is, the two lines are parallel to each other.

[0091] Among them, the above f is the focal length of the lens. The relationship between the focal length of the lens f, the target detection object, and the sensing element can be realized by the following formula:

[0092] L / l=W / w=D / f

[0093] Wherein, L is the height of the target object, l is the height of the sensing element, W is the width of the target object, w is the width of the sensing element, and D is the distance between the lens and the target object.

[0094] According to the above formula, we can get:

[0095] f=D×l / L=D×w / W

[0096] For example, if the height of the sensing element is 2mm, the detection target is 20M, and the target height is 1.7M, then f=20×2 / 1.7=23.5mm.

[0097] From the above formula, it can be seen that when the distance between the lens and the target object is farther, the lens surface is farther from the PIR distance (focal length f).

[0098] Assuming the coordinates of core 2 are (x2, y2), x2 and y2 can be expressed by the following formula:

[0099] x2=(d1+sqrt(d1 2 -(tan(θ1) 2 +1)×(d1 2 -4×tan(θ1) 2 ×f 2 )) / (2×(tan(θ1) 2 +1))

[0100] y2=(x2-d1 / 2) / tan(θ1)

[0101] By analogy, the angle between the line connecting the first PIR and core 2 (the core position of the first partition) and the Y-axis is θ2, and the angle between the line connecting core 3 (the core position of the second partition) and the second PIR and the Y-axis is also θ2, that is, the two lines are parallel to each other. According to the above formula and rules, the coordinates of other core positions can be determined in turn.

[0102] Figure 6 This is a schematic diagram of the propagation principle of infrared rays provided in the embodiment of the present application. Figure 6 As shown, when the edge incident angle (the angle β between the line connecting the local lens edge and the PIR center and the PIR surface normal) is large, there are problems of high reflection ratio and low incident efficiency, which will affect the accuracy and reliability of detection.

[0103] based on Figure 6 According to the principle shown, the partitioning of the lens also needs to meet at least one of the following conditions:

[0104] Condition 1: The width to height ratio of a single partition is controlled around 1:2, and the maximum does not exceed 1:8.

[0105] Condition 2: β is not greater than 60 degrees.

[0106] It should be understood that the lens partitions determined in the above manner can ensure that the area of ​​a single partition is large enough to improve the long-distance detection capability. In addition, it can also ensure that enough infrared rays are incident on the PIR to ensure the accuracy and reliability of detection.

[0107] At the same time, the line connecting the first PIR in the adjacent PIRs and the first subarea of ​​the lens is parallel to the line connecting the second PIR in the adjacent PIRs and the second subarea of ​​the lens, so that the bright area after the first PIR is projected by the lens overlaps and is parallel to the bright area after the second PIR is projected by the lens. This parallel setting allows the first PIR and the second PIR to perform signal mutual judgment within the bright area to improve detection accuracy. At the same time, the signals of the first PIR and the second PIR can also be superimposed to achieve signal detection enhancement.

[0108] It should be understood that the specific implementation method will be Fig.19 The embodiments shown are explained and will not be described in detail here.

[0109] Taking the pyroelectric lens system including two PIRs as an example, when the distance between adjacent PIRs is the maximum adjustable distance, that is, the bright area distribution under the set highest speed scene can be as follows: Figure 7 shown.

[0110] Figure 7 Schematic diagram of bright area distribution in the highest speed scenario provided in the embodiment of the present application Figure 1 .like Figure 7 As shown, Figure 7 Part (a) is the detection sector formed by the left PIR through the lens, and the detection sector includes the bright areas corresponding to the two sensing elements in the left PIR. Similarly, Figure 7The (b) part of the image is the detection sector formed by the lens of the right PIR. The detection sector includes the bright areas corresponding to the two sensing elements in the right PIR. The bright areas contained in these two detection sectors are highly overlapped and parallel. The two are merged. Figure 7 It is represented by part (c) of .

[0111] In practical applications, the angle α between adjacent viewing areas also affects the detection effect. Figure 8 Schematic diagram of the angles between adjacent viewing areas provided in the embodiment of the present application. Figure 8 As shown, the dark area is the bright area of ​​one sensing element in the PIR, the light area is the bright area of ​​another sensing element in the PIR, and the angle between adjacent viewing areas is α.

[0112] In practical applications, assuming that the moving speed of the target object is v, the detection distance (the distance between the lens and the target object) is D, the linear frequency is m, and the angular frequency is n, the linear frequency and angular frequency can be calculated by the following formula:

[0113] m = v / (2 × D × tan (α / 2))

[0114] n=2π×m

[0115] According to the above formula, the faster the target object moves, the higher the angular frequency; the closer the detection distance, the higher the angular frequency.

[0116] Fig. 9 The following is a schematic diagram of the relationship between PIR responsivity and frequency provided in the embodiment of the present application. Fig. 9 As shown, as the frequency gradually increases, the PIR responsivity K decreases, that is, the PIR signal value decreases, resulting in a lower detection rate for high-speed detection objects. In order to improve the detection effect of high-speed detection objects, it is necessary to reduce the number of partitions, that is, the α angle (the angle between adjacent viewing areas) needs to be large enough to reduce the frequency. In practical applications, the α angle can be in the range of 20 to 30 degrees. For example, taking a detection distance of 20 meters as an example, when the speed of the target detection object is 10m / s, the angular frequency is 5.8HZ, and when α is defined as 15 degrees, the angular frequency is 12HZ, which exceeds the responsivity in the specification. After performing a difference calculation, it was found that the PIR responsivity difference between the two would be more than 3 times.

[0117] For low-speed target detection, such as 3m / s, due to the large α, when the target detection object is far away from the pyroelectric lens system, it takes too long for the target detection object to move to the next bright area at a speed of 3m / s. Therefore, the distance between adjacent PIRs can be reduced so that the parallel detection sectors gradually become non-parallel and staggered. Fig.10 This is a schematic diagram of the bright area distribution in the lowest speed scenario provided in the embodiment of the present application. Fig.10As shown in the figure, in the set lowest speed scene, when the distance between adjacent PIRs is reduced to d1 / 2, a nearly uniformly distributed viewing area with doubled bright area can be obtained, which can achieve the effect of doubling the detection frequency to adapt to low-speed target detection. Since the aperture size of the partition remains unchanged, the detection distance will not be reduced due to the reduction in the number of partitions, ensuring the long-distance detection capability.

[0118] In the prior art, most of the detection range is achieved by using a PIR+lens to detect the target object. When the detection range requirement changes, the lens is usually replaced. Therefore, for one device, there is generally only one field of view.

[0119] Some solutions can also be implemented as multiple PIR+lenses, that is, each PIR plus its own lens to achieve superposition of field of view (the field of view can be spliced ​​or partitioned. For example, one PIR+lens can achieve large-range detection, and one PIR+lens can achieve local small-range detection).

[0120] Fig.11 Schematic diagram of the structure of 2 PIR+lenses in the prior art. Fig.11 As shown in the figure, two PIRs are used to achieve the splicing of the detection range. When the field of view angle requirement changes, one of the PIRs is removed to change the detection range. For example, if the original detection range angle is θ1+θ2, it will be θ1 or θ2 after removing one.

[0121] However, the detection range angle of the above zoom solution changes greatly and has poor continuity. In order to solve the above problem, the prior art increases the number of PIRs, and then removes a small number of PIRs to achieve a small change in the detection range angle.

[0122] However, the above solution requires a large number of PIRs and has a relatively complex structure. It is not compatible with most products and has poor feasibility.

[0123] In the present application, the processing module can also adjust the distance between adjacent PIRs to adjust the angle of the field of view, that is, to achieve zoom.

[0124] Fig.12 This is a schematic diagram of the edge incident angle provided in the embodiment of the present application. Fig.12 As shown, the edge incident angles are γ1 and γ2, and the core 4 coordinates are (a, b). Then γ1=a×tan((a-d1 / 2) / b), γ2=a×tan((a+d1 / 2) / b), and the detection field range is 2max(γ1, γ2).

[0125] As the processing module adjusts the distance between adjacent PIRs, the angle between the connection line between the edge PIR and the edge core of at least two PIRs and the Y axis (edge ​​incident angle) also changes, that is, the detection field of view changes, and the zoom effect can be achieved. When d1 becomes smaller, the field of view angle becomes smaller, and when d1 becomes larger, the field of view angle becomes larger.

[0126] It should be understood that the pyroelectric lens system may also be provided with a zoom knob. The user may determine the detection field of view range according to the actual scenario and rotate the zoom knob. Accordingly, the processing module responds to the user's rotation operation, obtains the detection field of view range set by the user, and then searches for the target distance corresponding to the detection field of view range in the preset mapping relationship, and adjusts the distance between adjacent PIRs according to the target distance.

[0127] That is to say, the preset mapping relationship includes not only the corresponding relationship between speed and distance, but also the relationship between field of view range and distance.

[0128] Optionally, in some embodiments, the pyroelectric lens system further comprises a light-proof baffle, which is detachably placed on at least one of the two sides of any PIR.

[0129] Optionally, the height of the light-tight baffle may be adjustable.

[0130] exist Figure 5 Based on this, a pyroelectric lens system including two PIRs is used as an example to illustrate: Fig.13 Schematic diagram of the position of the opaque baffle provided in the embodiment of the present application. Fig.13 As shown, a light-proof baffle can be placed between the two PIRs to shield the incident light of the right core 3 and core 4 for the first PIR, thereby realizing the change of the central side field of view γ1; at the same time, the incident light of the left core 3' and core 4' can be shielded for the second PIR, thereby realizing the change of the central side field of view γ2. Similarly, a light-proof baffle can be added on the outside, for example Fig.13 The opaque baffle on the right side of the second PIR blocks the incident light of the right core 4 for the second PIR, thereby realizing the change of the central side field of view γ1 and realizing the zoom function. The detection field of view range is 2max (γ1, γ2).

[0131] Optionally, in some embodiments, a silica gel filter is deployed above each PIR.

[0132] It should be understood that the material of the filter may also be other materials, which may be determined according to actual conditions, and the embodiments of the present application do not impose specific limitations on this.

[0133] In practical applications, the filter can be 5.5um flat pass or 8~14um band pass, and is fixed on the PIR in the form of silicone embedding. The gap between the filter and the PIR surface is between 0.1~2mm, which should not be too large. Too large will cause the edge detection field of view to be blocked and reduced.

[0134] Fig.14 Schematic diagram of the structure of the pyroelectric lens system provided in the embodiment of the present application Figure 2 .like Fig.14 As shown, the pyroelectric lens system also includes a filter.

[0135] Fig.15 This is a schematic diagram of the structure of the PIR+filter provided in the embodiment of the present application. Fig.15 As shown, the filter can completely cover the sensing element in the PIR.

[0136] In the above embodiment, by installing a filter on the surface of the PIR, a noise reduction effect can be achieved in outdoor application scenarios, thereby reducing the false alarm rate.

[0137] Optionally, the curved surface profile generatrix of the lens may be a spherical surface.

[0138] exist Fig.14 On the basis of Fig.16 Schematic diagram of the spatial coordinates of the pyroelectric lens system provided in the embodiment of the present application. Fig.16 As shown, the distance between the center positions of the two PIRs is the distance d1 between the two PIRs, and the straight-line distance between the PIR surface and the most convex point of the lens is the focal length f.

[0139] Considering that the effective area of ​​a cylindrical surface is larger than that of a spherical surface, based on the idea of ​​maximizing the aperture, the curved contour generatrix of the lens can also be a cylindrical surface, with no horizontal dispersion and vertical dispersion by setting at least two PIRs smaller than the size of the sensing element to be deployed on the center plane of the lens.

[0140] When the curved surface profile generatrix of the lens is a cylindrical surface, it has more advantages in light collection, allowing more infrared rays to pass through the lens and focus on the PIR, thereby improving the accuracy and reliability of detection.

[0141] Optionally, in some embodiments, the inner wall of the lens is a Fresnel focusing structure.

[0142] Fig.17 This is a schematic diagram of the inner wall of the lens provided in the embodiment of the present application. Fig.17 As shown, in actual applications, the tooth height is not higher than 0.2mm, the base surface thickness is not higher than 0.5mm, generally defined as 0.4~0.55mm, plus the tooth height, the overall thickness is not higher than 0.7mm.

[0143] In this embodiment, since the inner wall of the lens is a Fresnel focusing structure, the overall thickness of the lens can be effectively reduced, and the light transmittance of the lens is increased, so that more infrared rays can be injected into the PIR, thereby improving the accuracy and reliability of detection.

[0144] Fig.18 A three-dimensional schematic diagram of a pyroelectric lens system provided in an embodiment of the present application. Fig.18 As shown, the lens of the pyroelectric lens system is double-layer partitioned.

[0145] Based on the pyroelectric lens system involved in any of the above embodiments, a detection method for a target detection object based on the pyroelectric lens system is explained below.

[0146] Fig.19 Schematic diagram of the process of detecting a target object provided in the embodiment of the present application. Fig.19 As shown, the execution subject of the method is a processing module of the pyroelectric lens system involved in any of the above embodiments, and the method can be implemented by the following steps:

[0147] S191. Determine the target distance according to the speed of the target detection object and a preset mapping relationship.

[0148] The speed of the target object is obtained in response to the user's adjustment operation or collected by the speed sensor. The preset mapping relationship includes the corresponding relationship between speed and distance. The target distance is proportional to the speed of the target object.

[0149] In a possible implementation, the pyroelectric lens system further includes a speed adjustment knob. The user can determine the speed of the target detection object according to the actual scenario and adjust the speed adjustment knob. Correspondingly, the processing module responds to the user's adjustment operation, obtains the speed of the target detection object input by the user, and then searches for the target distance corresponding to the speed of the target detection object in the preset mapping relationship.

[0150] For example, in the field of wildlife detection, according to the living habits of wild animals generated in a fixed area, their average speed is determined. Before placing the surveillance camera in the fixed area, the speed adjustment knob is adjusted according to the average speed, so that the distance between adjacent PIRs in the pyroelectric lens system is subsequently adjusted according to the average speed.

[0151] In another possible implementation, the pyroelectric lens system further includes a speed detection sensor, which is used to determine the speed of the target detection object. After detecting the speed of the target detection object, the speed detection sensor sends the speed of the target detection object to the processing module, and the processing module searches in a preset mapping relationship according to the speed of the target detection object to determine the target distance corresponding to the speed of the target detection object.

[0152] In practical applications, the speed detection sensor will determine the speed of a moving object in real time, and the moving object can be a target detection object or a non-target detection object. Afterwards, the target speed is actually determined based on the detected speed of the moving object, so that the distance between adjacent PIRs in the discharge lens system can be adjusted in real time based on the target speed to ensure that the detection requirements of target detection objects with different speeds are better met, thereby improving the detection flexibility and accuracy.

[0153] S192. Adjust the distance between adjacent PIRs in the pyroelectric lens system according to the target distance.

[0154] In one possible implementation, when decreasing the distance between adjacent PIRs, the PIRs may be controlled to move toward the central axis of the lens until the distance between adjacent PIRs reaches the target distance; when increasing the distance between adjacent PIRs, the PIRs may be controlled to move away from the central axis of the lens until the distance between adjacent PIRs reaches the target distance.

[0155] S193. Detect the target object through the pyroelectric lens system.

[0156] For the highest speed scenario, the line connecting the first PIR in the adjacent PIRs and the first partition of the lens is parallel to the line connecting the second PIR in the adjacent PIRs and the second partition of the lens; the first partition and the second partition are adjacent partitions in the lens, and the relative position relationship between the first partition and the second partition is the same as the relative position relationship between the first PIR and the second PIR. The distribution of the bright area can be referred to Figure 7 Schematic diagram shown.

[0157] Fig. 20 This is a schematic diagram of electrical signals in the highest speed scenario provided in the embodiment of the present application. Fig. 20 As shown, in Figure 7 On the basis of, when the target object enters the detection area tangentially and moves continuously until it leaves the detection area, the two PIRs will generate electrical signals at the same time. Ideally, the two electrical signals will form waveforms of the same type and phase. The blue line is the waveform formed by the left PIR, and the red line is the waveform formed by the right PIR.

[0158] in, Fig. 20The horizontal axis of the waveform shown is time, and the vertical axis is amplitude.

[0159] Based on the above waveform characteristics, the electrical signal generated by the PIR can be subjected to signal mutual judgment to improve the accuracy of detection.

[0160] Specifically, when any PIR generates an electrical signal, timing starts, and before the accumulated duration obtained by timing reaches a preset duration, it is determined whether other PIRs generate electrical signals; if any other PIR does not generate an electrical signal, it is determined that the target object is not detected; if other PIRs all generate electrical signals, the electrical signals generated by each PIR are superimposed, and the target object is detected according to the superimposed electrical signals.

[0161] In the highest speed scenario of this setting, if all PIRs generate electrical signals within the preset time, it means that all PIRs have detected changes in infrared radiation. At this time, the electrical signal is credible, and the target object can be detected based on the electrical signals generated by all PIRs; if some PIRs generate electrical signals within the preset time, but some PIRs do not, it means that there may be a PIR failure or misdetection caused by environmental factors. At this time, the electrical signal is unreliable, and it is determined that the target object is not detected. In this way, signal mutual judgment is achieved, which further improves the accuracy of detecting the target object based on the electrical signal.

[0162] Furthermore, after determining that the electrical signal is credible, the electrical signals generated by all PIRs can be superimposed to form an effective signal gain, and then the target object can be detected based on the superimposed electrical signal, thereby improving the signal-to-noise ratio and effectively increasing the detection rate.

[0163] It should be understood that Fig. 20 The yellow dotted line in the figure is the superimposed electrical signal.

[0164] Furthermore, in the above-mentioned highest-speed scenario, a light-proof baffle can be detachably placed on the left side of the leftmost PIR and on the right side of the rightmost PIR, so as to shield the incident light of the leftmost partition of the lens of the pyroelectric lens system for the remaining PIRs except the rightmost PIR, and shield the incident light of the rightmost partition of the lens of the pyroelectric lens system for the remaining PIRs except the rightmost PIR. At this time, the incident light of the rightmost partition of the lens can only be captured by the leftmost PIR, and the incident light of the leftmost partition of the lens can only be captured by the rightmost PIR.

[0165] exist Figure 7 Based on the embodiment shown, after the opaque baffle is detachably placed on the left side of the leftmost PIR and the right side of the rightmost PIR, the bright area distribution can be obtained by Fig.21 To express. Fig.21 Schematic diagram of bright area distribution in the highest speed scenario provided in the embodiment of the present application Figure 2 .like Fig.21 As shown, the left PIR does not construct the right core 4 visual area, and the right PIR does not construct the left core 4' visual area. At this time, the entire detection area can be divided into three parts, where part 1 includes the left PIR single response sector, part 2 includes the left and right PIR dual response sectors, and part 3 is the right PIR single response sector.

[0166] In this scenario, after the target object is detected, the position of the target object is determined based on the PIR that generates the electrical signal.

[0167] by Fig.21 For example, after determining that the target object is detected based on the electrical signal, if both PIRs generate electrical signals, it is determined that the target object is in part 3; if the electrical signal generated by the left PIR is, it is determined that the target object is in part 1; if the electrical signal generated by the right PIR is, it is determined that the target object is in part 3.

[0168] In this embodiment, by determining the approximate position of the target detection object, the monitoring camera can be assisted to better photograph the target detection object, thereby providing assistance for subsequent operations of the monitoring camera.

[0169] It should be understood that in the highest speed scenario, if the bright areas of all PIRs overlap in parallel, the detection accuracy and detection rate can be increased by mutual judgment and superposition of signals; if the partial bright areas of all PIRs do not overlap by placing an opaque baffle, the position of the target detection object can be determined based on the PIR that generates the electrical signal.

[0170] Optional, based on Fig.10 In the lowest speed scenario shown, the visual areas of the left PIR and the right PIR are not overlapped and parallel. When the target object invades tangentially (horizontally from left to right or from right to left in the figure), there is a phase difference in the signals of the two PIRs, and the two PIRs need to detect the target object through their own judgment logic.

[0171] based on Fig.10 The lowest speed scenario shown, Fig. 22 This is a schematic diagram of electrical signals in the lowest speed scenario provided in the embodiment of the present application. Fig. 22 As shown, Fig. 22 Where a means tangential walking through at least one visual area corresponding to the left PIR and the visual area corresponding to the right PIR, and b means only passing through the right PIR (local walking).

[0172] in, Fig. 22 The horizontal axis of the waveform shown is time, and the vertical axis is amplitude.

[0173] Further, in Figure 7 The scenes shown and Fig.10In the scenario shown, low-speed detection objects are detected respectively, and the electrical signal generated by PIR can be Fig.23 and Fig.24 To express.

[0174] Fig.23 An electrical signal generated for a low-speed detection object in the highest-speed scenario provided in an embodiment of the present application. Fig.24 The electrical signal generated for the low-speed detection object in the lowest speed scenario provided by the embodiment of the present application. Fig.23 and Fig.24 As shown in the figure, in the lowest speed scene, the light and dark areas are evenly distributed, there is no large blank area, and the angular frequency distribution is high. Compared with the highest speed scene, for low-speed detection objects, the detection effect can be twice that of the highest speed detection object, and the detection rate is high.

[0175] in, Fig.23 and Fig.24 The horizontal axis of the waveform shown is time, and the vertical axis is amplitude.

[0176] The detection method of the target object provided in the embodiment of the present application is applied to the processing module in the pyroelectric lens system, and the target distance is determined according to the speed of the target object and the preset mapping relationship; the distance between adjacent passive infrared detectors PIR in the pyroelectric lens system is adjusted according to the target distance; and the target object is detected through the pyroelectric lens system. Among them, the speed of the target object is obtained in response to the user's adjustment operation or acquired according to the speed sensor, the preset mapping relationship includes the corresponding relationship between the speed and the distance, and the target distance is proportional to the speed of the target object. In this technical solution, considering that the target objects with different speeds have different requirements for the bright area of ​​the pyroelectric lens system, the distance between adjacent PIRs can be adjusted according to the manually set speed or the speed acquired by the speed sensor to generate a bright area using the speed of the target object, thereby improving the detection effect of the target object.

[0177] Optionally, in some embodiments, the present application also provides a monitoring camera, in which the pyroelectric lens system is configured.

[0178] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A pyroelectric lens system, characterized in that: include: A lens, at least two passive infrared detectors PIR and a processing module; The cross-sectional baseline of the lens is in an arc shape, and the at least two PIRs are parallel to each other and are arranged on the same plane on the concave side of the lens; Each PIR comprises at least two sensing elements, the at least two sensing elements are arranged in parallel, and a line connecting the at least two sensing elements is parallel to a line connecting the at least two PIRs; The processing module is used to adjust the distance between adjacent PIRs to detect the target object, and the distance between adjacent PIRs is proportional to the speed of the target object.

2. The system according to claim 1, characterized in that For any adjacent PIRs, when the distance between the adjacent PIRs is the maximum adjustable distance, a line connecting a first PIR among the adjacent PIRs and a first subarea of ​​the lens is parallel to a line connecting a second PIR among the adjacent PIRs and a second subarea of ​​the lens; The first partition and the second partition are adjacent partitions in the lens, and a relative positional relationship between the first partition and the second partition is the same as a relative positional relationship between the first PIR and the second PIR.

3. The system according to claim 1 or 2, characterized in that: The pyroelectric lens system further includes a light-proof baffle, which is detachably placed on at least one of the two sides of any PIR.

4. The system according to claim 1 or 2, characterized in that: The pyroelectric lens system further comprises a speed detection sensor, which is used to determine the speed of the target detection object and send it to the processing module; The processing module is used to adjust the distance between the adjacent PIRs according to the speed of the target detection object and a preset mapping relationship, wherein the preset mapping relationship includes a corresponding relationship between speed and distance.

5. The system according to claim 1 or 2, characterized in that: The curved surface profile generatrix of the lens is a cylindrical surface, and the at least two PIRs are deployed on the center plane of the lens.

6. The system according to claim 1 or 2, characterized in that: A silica gel filter is deployed above each PIR.

7. The system according to claim 1 or 2, characterized in that: The inner wall of the lens is a Fresnel focusing structure.

8. A method for detecting a target object, characterized in that: A processing module applied to a pyroelectric lens system according to any one of claims 1 to 7, the method comprising: Determine the target distance according to the speed of the target detection object and a preset mapping relationship, wherein the speed of the target detection object is obtained in response to an adjustment operation of the user or is acquired according to a speed sensor, and the preset mapping relationship includes a corresponding relationship between the speed and the distance, and the target distance is proportional to the speed of the target detection object; According to the target distance, adjusting the distance between adjacent passive infrared detectors PIR in the pyroelectric lens system; The target detection object is detected through the pyroelectric lens system.

9. The method according to claim 8, characterized in that When the pyroelectric lens system is a structure as shown in claim 2, and the distance between the adjacent PIRs is an adjustable maximum distance, the target detection object is detected by the pyroelectric lens system, including: When any PIR generates an electrical signal, timing is started, and before the accumulated time obtained by timing reaches a preset time, it is determined whether other PIRs generate electrical signals; If any other PIR does not generate an electrical signal, it is determined that the target detection object is not detected; If the other PIRs all generate electrical signals, the electrical signals generated by each PIR are superimposed, and the target object is detected according to the superimposed electrical signals.

10. The method according to claim 8, characterized in that When the pyroelectric lens system is of the structure as shown in claim 2, and the opaque baffle is detachably placed on the left side of the leftmost PIR and on the right side of the rightmost PIR, so as to shield the incident light of the leftmost subarea of ​​the lens of the pyroelectric lens system for the remaining PIRs except the rightmost PIR, and shield the incident light of the rightmost subarea of ​​the lens of the pyroelectric lens system for the remaining PIRs except the leftmost PIR, the method further comprises: After the target object is detected, the position of the target object is determined according to the PIR that generates the electrical signal.

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