A 3D structured light module and a terminal device

Abstract

The application provides a 3D structured light module and a terminal device, the 3D structured light module is installed on the terminal device, and the 3D structured light module comprises a front shell and an optical module; the front shell comprises oppositely arranged front and rear surfaces, and a preset inclination angle is formed between the front and rear surfaces; the optical module is installed on one side of the rear surface of the front shell; the optical module comprises a speckle projector, an infrared light supplementing light source, an infrared receiving camera and a circuit board; the speckle projector, the infrared light supplementing light source and the infrared receiving camera are all fixed on the circuit board; the infrared light supplementing light source is arranged between the speckle projector and the infrared receiving camera; wherein the preset inclination angle is 5-15 degrees. The application ensures that the 3D structured light module assembled to any terminal device can maintain a uniform inclination angle, reduces assembly deviation, and improves assembly precision and structural stability.

Description

Technical Field

[0001] This invention relates to the field of 3D visual sensing technology, specifically to a 3D structured light module for use in smart door locks. Background Technology

[0002] With the upgrading of home security needs, smart door locks equipped with 3D structured light recognition have become mainstream products. The 3D structured light module relies on the VCSEL speckle projector to emit infrared speckle, and the infrared camera collects the reflected light and calculates the depth information, which can accurately complete the liveness detection and facial identity verification, and has a higher level of security compared with 2D image recognition.

[0003] Existing 3D structured light modules used in smart door locks have several shortcomings in practical use, as follows: Limited field of view for recognition: Due to the diffraction angle of diffractive optical elements and the module installation method, the effective recognition range of conventional modules is relatively small; when tall users stand close to the door, their faces are outside the field of view, making it impossible to unlock the door, which seriously affects the user experience.

[0004] Optical crosstalk is a prominent issue: the internal structure and window layout of smart lock bodies vary among different brands and models. The layout of light sources and cameras in conventional assembly does not have a specific anti-crosstalk design. After being assembled into some lock bodies, the light emitted from the light source can easily enter the infrared receiving camera directly or through the cover plate of the lock body, forming optical crosstalk, causing a surge in stray light in the image and recognition failure.

[0005] Poor assembly tilt accuracy: Existing modules rely on the height difference of different positioning posts in the lock body to achieve overall tilting, thereby adapting to the face recognition area. This method is greatly affected by the machining tolerance and assembly tolerance of the lock body. When different door locks are equipped with the same module, the actual tilt angle and effective field of view deviate significantly, resulting in poor product consistency and difficulty in ensuring the stability of mass production and use.

[0006] Therefore, developing a 3D structured light module with a large recognition field of view, effective suppression of light crosstalk, and high assembly precision for the operating conditions of smart door locks is an urgent problem to be solved in this field. Summary of the Invention

[0007] This invention provides a 3D structured light module and a terminal device. By setting a preset tilt angle between the front and rear surfaces of the front shell, the module can achieve face coverage in a vertically large field of view under small tilt angle installation conditions. At the same time, it ensures that the 3D structured light module can maintain a uniform tilt angle when assembled to any terminal device, reducing assembly deviation and improving assembly accuracy and structural stability.

[0008] In a first aspect, embodiments of the present invention provide a 3D structured light module, which is installed on a terminal device and includes a front shell and an optical module; the front shell includes a front surface and a rear surface disposed opposite to each other, and a preset tilt angle is formed between the front surface and the rear surface. The optical module is mounted on one side of the rear surface of the front housing; The optical module includes a speckle projector, an infrared supplementary light source, an infrared receiving camera, and a circuit board; the speckle projector, the infrared supplementary light source, and the infrared receiving camera are all fixed on the circuit board; the infrared supplementary light source is arranged between the speckle projector and the infrared receiving camera; The preset tilt angle is 5°~15°.

[0009] Optionally, the front housing is also provided with positioning and locking holes. The positioning and locking hole structure includes a second fixing hole and a first fixing hole. The second fixing hole is used to engage with the positioning post on the terminal device to achieve pre-positioning, and the first fixing hole is used for fasteners to pass through to fix the front housing and the terminal device.

[0010] Optionally, the speckle projector includes a diffractive optical element with a vertical diffraction angle ≥100°, a depth processing tolerance controlled within ±5%, and an overlay deviation controlled within 100nm. The infrared receiving camera includes an infrared receiving lens, the vertical field of view of the infrared receiving lens is ≥100°, and the overall optical distortion of the infrared receiving lens is ≤2%.

[0011] Optionally, the terminal device has an opening on the surface facing the user, the position of the opening corresponds to the front shell, and a light-transmitting cover is installed on the opening. The thickness of the light-transmitting cover is t, and the refractive index of infrared light is n. The front surface of the front shell is parallel to the light-transmitting cover; The front cover also includes a light-blocking structure, which is located between the infrared supplementary light source and the infrared receiving camera. The light-blocking structure is used to limit the maximum emission angle θ3 of the infrared supplementary light source towards the light-transmitting cover plate, and to block the direct beam transmission path between the infrared supplementary light source and the infrared receiving camera below the light-transmitting cover plate. Within the baseline plane of the infrared supplementary light source and the infrared receiving camera, the minimum horizontal distance L between the points where the light emitted from the infrared supplementary light source and the light incident from the infrared receiving camera lands on the side of the light-transmitting cover closest to the front shell satisfies: L≥7*t*tan(arcsin(sinθ3 / n)).

[0012] Optionally, the minimum horizontal spacing L satisfies: L≤9*t*tan(arcsin(sinθ3 / n)).

[0013] Optionally, the infrared supplementary lighting source includes an optical chip. Within the baseline plane of the infrared supplementary lighting source and the infrared receiving camera, the minimum light emission angle θ2 of the infrared supplementary lighting source, defined by the light-blocking structure, satisfies: θ2≥arctan((d*tanθ0+Bs / 2) / D); Where θ0 is the semi-mechanical field of view of the infrared receiving camera on the side away from the infrared supplementary light source, B is the baseline distance between the optical axis of the infrared receiving camera and the optical axis of the infrared supplementary light source, s is the width of the optical chip of the infrared supplementary light source in the baseline direction, and D is the distance from the nearest measured object to the optical chip.

[0014] Optionally, a light source elevation block may also be included; The infrared supplementary light source is fixed to the circuit board by a light source elevation block; Within the baseline plane of the infrared supplementary light source and the infrared receiving camera, the first distance between the top surface of the infrared supplementary light source and the circuit board is less than the second distance between the top surface of the infrared receiving camera and the circuit board, and the difference between the first distance and the second distance is 0~0.2mm.

[0015] Optionally, the front surface of the front housing is provided with a speckle projector light emission clearance hole, an infrared supplementary light source light emission clearance hole, an infrared supplementary light source light emission clearance groove, and an infrared receiving camera light emission clearance hole in sequence along the first direction. The front shell has a first end and a second end opposite each other in a second direction, and the thickness of the front shell gradually increases from the first end to the second end; The infrared supplementary light source emission clearance slot is located on the light-blocking structure on the side of the infrared supplementary light source emission clearance hole closest to the infrared receiving camera emission clearance hole, near the second end. Used to provide an unobstructed light path for the emitted light from the infrared supplementary light source, avoiding the front shell from blocking the supplementary light.

[0016] Optionally, the edges of the light-emitting clearance holes of the speckle projector, the infrared supplementary light source, and the infrared receiving camera are all provided with sealing adhesive grooves; the sealing adhesive grooves are used to fill with sealant to form a sealed connection between the light-emitting clearance holes of the speckle projector and the speckle projector, between the light-emitting clearance holes of the infrared supplementary light source and the infrared supplementary light source, and between the light-emitting clearance holes of the infrared receiving camera and the infrared receiving camera.

[0017] Secondly, embodiments of the present invention provide a terminal device, which includes a smart door lock; The smart door lock includes a lock body shell, a light-transmitting cover, and a 3D structured light module of any one of the first aspects; The lock body shell is the surface facing the user. The lock body shell has an opening, the position of which corresponds to the front shell of the 3D structured light module. A light-transmitting cover is installed on the opening. The front surface of the front shell is parallel to the light-transmitting cover; The light-emitting side of the 3D structured light module faces the light-transmitting cover plate.

[0018] This invention provides a 3D structured light module and a terminal device. By setting a preset tilt angle of 5°~15° between the front and rear surfaces of the front shell, the module can achieve ultra-large vertical field of view for face coverage even under small tilt angle installation conditions. This effectively reduces the installation tilt angle of the module on the terminal device, significantly reduces facial perspective distortion caused by large tilt angle installation, improves the stability and recognition success rate of the face recognition algorithm, and ensures that the 3D structured light module maintains a uniform tilt angle when assembled on any terminal device, reducing assembly deviation and improving assembly accuracy and structural stability. By designing the vertical diffraction angle of the speckle projector's diffraction optical element to be ≥100° and the vertical field of view of the infrared receiving lens to be ≥100° with lens distortion controlled within ≤2%, the module achieves ultra-large face coverage while maintaining a small tilt angle shell appearance. Furthermore, through an eight-step microstructure design and strict processing tolerance control (depth tolerance ±5%, overlay deviation within 100nm), the module achieves even greater coverage. This design ensures uniform brightness and a high signal-to-noise ratio across the entire field of view, thus solving the problem of traditional structured light modules requiring large-angle installation due to insufficient vertical field of view (usually ≤70°), which leads to severe perspective distortion affecting recognition accuracy. By setting a light-blocking structure on the front shell between the infrared supplementary light source and the infrared receiving camera, and using a formulaic constraint (L≥7*t*tan(arcsin(sinθ3 / n))) to control the distance between the landing points of the two beams inside the light-transmitting cover, the direct beam transmission path between the infrared supplementary light source and the infrared receiving camera is structurally blocked. This effectively avoids the image whitening and contrast reduction caused by the light from the light source entering the camera's field of view after refraction through the light-transmitting cover. At the same time, by setting a light-avoiding structure for the infrared supplementary light source, the light from the effective emitting area of ​​the light source is ensured to be emitted without obstruction. The height difference between the light source and the camera is adjusted within the range of 0~0.2mm by using a light source elevation block, ensuring that the supplementary light spot and the camera's field of view are precisely aligned at the target working distance, thus balancing anti-cross-lighting and supplementary light effects. Attached Figure Description

[0019] Figure 1 A schematic diagram of a traditional 3D structured light module provided as a background technology; Figure 2 This is a front view schematic diagram of a 3D structured light module provided in an embodiment of the present invention; Figure 3 This is a side view diagram of a 3D structured light module provided in an embodiment of the present invention; Figure 4 This is a side view cross-sectional diagram of a 3D structured light module provided in an embodiment of the present invention; Figure 5This is a schematic diagram of the rear view structure of a 3D structured light module provided in an embodiment of the present invention; Figure 6 An exploded view of a 3D structured light module provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the rear view structure of a front shell provided in an embodiment of the present invention; Figure 8 This is a cross-sectional schematic diagram of another 3D structured light module provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the optical path of a 3D structured light module provided in an embodiment of the present invention; Figure 10 This is a side view cross-sectional diagram of a terminal device provided in an embodiment of the present invention; Figure 11 This is a schematic diagram of the rear view structure of a terminal device provided in an embodiment of the present invention; Figure 12 This is an exploded view of the structure of a terminal device provided in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be fully described below with reference to the accompanying drawings in the embodiments of this invention, through specific implementation methods. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort fall within the protection scope of this invention.

[0021] Figure 1 This is a schematic diagram of a traditional 3D structured light module provided as a background technology, for reference. Figure 1 In the prior art, a traditional 3D structured light module 1 includes: a traditional terminal device 2, a traditional front shell 3, a traditional rear shell 4, a traditional motherboard 5, traditional foam 6, and screw posts 7. The traditional rear shell 4 is a thin steel sheet structure, and multiple metal fixing lugs with holes (not shown in the figure) extend from the rear shell 4 as fixing positions. The screw posts 7 are fixedly connected to the metal fixing lugs. The screw posts 7 of different heights form a height difference, which makes the traditional 3D structured light module 1 tilt at an angle to adapt to the recognition field of view.

[0022] The traditional 3D structured light module 1 has the following problems; 1. Poor tilt angle accuracy: The tilt angle is determined by the height difference of the screw column 7 and is affected by multiple factors such as the machining tolerance of the lock body, the compression tolerance of the foam 6, and the assembly tolerance. When the same traditional 3D structured light module 1 is equipped with different lock bodies, the tilt angle and the actual imaging field of view are very different, resulting in poor product consistency.

[0023] 2. Low structural strength: The back shell 4 is made of thin steel sheet, which is weak and easily deformed by vibration and compression. Long-term use will cause optical components to shift, affecting recognition accuracy.

[0024] 3. Insufficient protection: There is no dedicated protective structure, and the optical lens and light source are easily scratched and damaged by the terminal equipment during the assembly process.

[0025] 4. Weak anti-crosslight capability: The layout of the light source and camera does not have a specific stray light avoidance design, and crosslighting occurs frequently when combined with some locking mechanisms.

[0026] Figure 2 This is a front view schematic diagram of a 3D structured light module provided in an embodiment of the present invention. Figure 3 This is a side view diagram of a 3D structured light module provided in an embodiment of the present invention. Figure 4 This is a side view cross-sectional diagram of a 3D structured light module provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the rear view structure of a 3D structured light module provided in an embodiment of the present invention. Figure 6 An exploded view of a 3D structured light module provided in an embodiment of the present invention. (Reference) Figures 2-6 According to the first aspect of the present invention, the present invention provides a 3D structured light module 100, which is installed on a terminal device 200 and includes a front shell 10 and an optical module; the front shell 10 includes a front surface 11 and a rear surface 12 disposed opposite to each other, and a preset tilt angle is formed between the front surface 11 and the rear surface 12. The optical module is mounted on one side of the rear surface 12 of the front housing 10; The optical module includes a speckle projector 20, an infrared supplementary light source 30, an infrared receiving camera 40, and a circuit board 60; the speckle projector 20, the infrared supplementary light source 30, and the infrared receiving camera 40 are all fixed on the circuit board 60; the infrared supplementary light source 30 is arranged between the speckle projector 20 and the infrared receiving camera 40. The preset tilt angle α is 5°~15°.

[0027] The 3D structured light module 100 can be understood as a three-dimensional depth sensing module based on the principle of structured light. By projecting a specific infrared speckle pattern and receiving the pattern deformation after reflection from an object, it calculates the depth information of the object, realizing functions such as 3D face recognition, liveness detection, and distance measurement. The terminal device 200 can be understood as the final application device (such as a smart door lock, a face recognition card reader, or a payment terminal) on which the 3D structured light module 100 is installed. The preset tilt angle α can be understood as the fixed angle formed between the front surface 11 and the rear surface 12 of the front shell 10. This angle is used to ensure that when the 3D structured light module 100 is installed on the terminal device 200, the output optical axis of the optical module forms a certain pitch compensation angle with the normal direction of the front of the device. This is to adapt to the installation tilt angle and field of view requirements of different terminal devices (such as smart door locks and card readers), and to ensure that the receiving field of view of the infrared receiving camera 40, the infrared speckle emitted by the speckle projector 20, and the illumination area of ​​the infrared supplementary light source 30 can cover the depth measurement range of the target area.

[0028] For details, please refer to Figures 2-6 The preset tilt angle α between the front surface 11 and the rear surface 12 ensures that the optical axis of the optical module (speckle projector 20, infrared supplementary light source 30, and infrared receiving camera 40) forms a certain compensation angle with the front normal direction of the terminal device 200. This tilt angle can compensate for the difference in installation tilt angle of different terminal devices, ensuring that the infrared speckle pattern projected by the speckle projector 20 and the illumination area of ​​the infrared supplementary light source 30 can cover the target detection area (such as the face area), and that the infrared receiving camera 40 can receive the complete reflected signal, avoiding field of view obstruction or depth measurement blind spots caused by the tilt of the module installation angle. This application utilizes the preset tilt angle of the front surface 11 to tilt the entire optical field of view upward, accurately aligning it with the high area where faces typically appear, and can also completely capture the face of tall users at close range (when installed horizontally, the area below the field of view corresponds to the lower half of the person and is an invalid recognition area), greatly improving the recognition range and user experience.

[0029] The 3D structured light module provided in this embodiment of the invention simplifies the installation and positioning process of the 3D structured light module on the terminal device by using a preset tilt angle between the front and rear surfaces. Compared with the fixing method of the prior art, the tilt angle is directly integrated into the front shell, and the angle is guaranteed by the injection molding precision. It is not affected by multiple factors such as lock body processing tolerance, foam compression tolerance, and assembly tolerance. After being installed on different terminal devices, the tilt angle and field of view are small, the field of view range is highly consistent, and the product consistency is high.

[0030] In one specific embodiment, the 3D structured light module 100 adopts a time-division lighting and synchronous acquisition working mode. The speckle projector 20 and the infrared supplementary light source 30 are alternately lit, and the infrared receiving camera 40 synchronously acquires images throughout the process. When the speckle projector 20 is lit, the infrared receiving camera 40 synchronously acquires infrared speckle images. The speckle images are processed by algorithms to generate target depth images. These depth images are mainly used for liveness detection. By analyzing the depth information and three-dimensional shape of targets such as faces and hands, they can distinguish real human bodies from forged photos and videos, improving the security level of terminal devices such as door locks. Simultaneously, the depth data can assist in the three-dimensional feature comparison of faces and hands, participating in identity recognition. When the infrared supplementary light source 30 is lit, the infrared receiving camera 40 synchronously acquires two-dimensional infrared scene images. Two-dimensional infrared images record two-dimensional features such as the contours and textures of faces and hands, which are directly used for identity recognition and comparison. Combined with depth images, this forms a dual recognition mechanism of "two-dimensional features + three-dimensional liveness detection," balancing the dual requirements of recognition speed (rapid two-dimensional feature comparison) and security (three-dimensional depth liveness detection). In this time-division multiplexing mode, the speckle projector 20 and the infrared supplementary light source 30 are alternately activated in sequence, preventing optical signal crosstalk. The infrared receiving camera 40 acquires speckle images and infrared images in corresponding time slots, achieving precise frame synchronization through a timing control unit. This mode fully utilizes the same infrared receiving camera 40 to achieve dual-mode acquisition of depth and infrared images without increasing hardware costs.

[0031] Continue to refer to Figures 2-6 In an optional embodiment, the front shell 10 is further provided with a positioning and fixing structure 110. The positioning and fixing structure 110 includes a first fixing hole 111 and a second fixing hole 112 arranged coaxially. The first fixing hole 111 is used to engage with the positioning post 201 on the terminal device to achieve pre-positioning. The second fixing hole 112 is used for fasteners to pass through, so as to fix the front shell 10 and the terminal device 200.

[0032] Specifically, during installation, the positioning post 201 on the terminal device 200 is first engaged with the first fixing hole 111 to achieve pre-positioning between the module and the terminal device 200. After pre-positioning, fasteners (such as screws) are passed through the second fixing hole 112 and screwed into the corresponding threaded hole or nut on the terminal device 200 to securely lock the front cover 10 to the terminal device 200.

[0033] Figure 7 This is a rear view schematic diagram of a front shell structure provided in an embodiment of the present invention, with reference to... Figure 5A rear shell 50 is also provided on one side of the rear surface 12 of the front shell 10. The circuit board 60 is fixed to the inside of the front surface 11 (i.e., the rear surface 12 side) by screws, and the rear shell 50 is also locked to the front surface 11 by screws, forming a protective structure for the circuit board 60 by the front shell 10 and the rear shell 50. (Reference) Figure 7 On the rear surface 12 sides, circuit board positioning posts 106 and circuit board screw holes 108 are reserved for fixing the circuit board 60 in a preset position. The positioning and locking are integrated, and it can be directly engaged with the lock body positioning posts for pre-positioning, combining positioning and locking functions. This structure eliminates unnecessary assembly processes, reduces cumulative tolerances, and significantly improves the assembly accuracy of the module and the lock body. At the same time, it is compatible with the positioning structure of different lock body styles, making it more versatile.

[0034] Optionally, the speckle projector 20 includes a diffraction optical element, wherein the vertical diffraction angle of the diffraction optical element is ≥100°, the depth processing tolerance is controlled within ±5%, and the overlay deviation is controlled within 100nm. The infrared receiving camera 40 includes an infrared receiving lens, the vertical field of view of the infrared receiving lens is ≥100°, and the overall optical distortion of the infrared receiving lens is ≤2%.

[0035] Specifically, in order to achieve full coverage of the face with a small tilt housing and realize an ultra-large recognition field of view in the vertical direction, this application has carried out special optical optimization of the diffractive optical element and the infrared receiving lens.

[0036] For the diffractive optical element, its vertical diffraction angle is designed to be ≥100° to ensure that the speckle projector 20 can cover the entire height range of the face in the vertical direction. The DOE adopts an eight-step microstructure design, which optimizes the light field energy distribution to solve the problem of poor light uniformity under a large field of view, making the projected speckle pattern uniform in brightness and with good contrast throughout the entire field of view. At the same time, the optical processing tolerance is strictly controlled: the depth processing tolerance of the DOE is controlled within ±5% (to ensure the consistency of diffraction efficiency), and the overlay deviation is controlled within 100nm (to ensure the alignment accuracy between multiple steps), thereby ensuring uniform speckle brightness and high signal-to-noise ratio throughout the entire field of view, and avoiding uneven brightness or local missing speckle patterns due to processing errors. For the infrared receiving lens, the vertical field of view angle is designed to be ≥100° to ensure that the infrared receiving camera 40 can receive the reflected light signal covering the entire target face area. The overall optical distortion of the lens is controlled to ≤2% to avoid image distortion and feature distortion at the edge of the large field of view, and to ensure the accuracy of face and palm feature recognition throughout the entire field of view.

[0037] It should be noted that traditional optical devices of this type typically have a vertical field of view of only 70°, requiring a large tilt angle (e.g., 20°-30°) to cover the face area. However, a large tilt angle can cause severe perspective distortion (such as face stretching and disproportion), interfering with the recognition algorithm and reducing recognition accuracy. This solution uses a large field of view optical element, combined with a small tilt angle of 5°~15°, which can cover faces of varying heights without a large tilt angle, significantly reducing perspective distortion, resulting in higher recognition accuracy and a better user experience.

[0038] Figure 8 This is a cross-sectional schematic diagram of another 3D structured light module provided in an embodiment of the present invention. Figure 9 This is a schematic diagram of the optical path of a 3D structured light module provided in an embodiment of the present invention, with reference to... Figures 8-9 In an optional embodiment, the terminal device 200 has an opening on its surface facing the user, the opening being positioned corresponding to the front housing 10. A light-transmitting cover 202 is mounted on the opening, the light-transmitting cover 202 having a thickness of t and a refractive index of n for infrared light. The front surface of the front housing 10 is parallel to the light-transmitting cover 202. The front housing 10 also includes a light-blocking structure 107, located between the infrared supplementary light source 30 and the infrared receiving camera 40. The light-blocking structure 107 is used to limit the infrared supplementary light source 30 from shining into the light-transmitting cover 202. The maximum emission angle θ3 of the light cover 202 is blocked, and the direct beam transmission path between the infrared supplementary light source 30 and the infrared receiving camera 40 is blocked below the light cover 202. In the baseline plane of the infrared supplementary light source 30 and the infrared receiving camera 40, the minimum horizontal distance L between the light emitted from the infrared supplementary light source 30 and the light incident on the infrared receiving camera 40 on the side of the light cover 202 near the front shell 10 satisfies: L≥7*t*tan(arcsin(sinθ3 / n)).

[0039] The baseline plane can be understood as a vertical plane that passes through both the optical axis of the infrared receiving camera 40 and the optical axis of the infrared supplementary light source 30. The minimum horizontal distance L can be understood as the horizontal distance between two points on the inner side of the light source 30 (optical chip 32) near the infrared receiving camera 40 and the light source 30 near the infrared supplementary light source 30 within the baseline plane, respectively. It should be noted that the light-transmitting cover 202 can transmit infrared light, and depending on the appearance design requirements of the terminal device, it can be selected to transmit visible light or be essentially opaque to visible light (e.g., using an infrared-transmitting, visible-light-blocking filter or black infrared-transmitting ink glass).

[0040] Specifically, the light-transmitting cover 202 is installed on the opening of the terminal device 200 facing the user. The front surface 11 of the front shell 10 is parallel to the light-transmitting cover 202, and the overall height of the shell is higher than the top surface of the optical device. During assembly and use, it can effectively protect the infrared supplementary light source 30 and the infrared receiving camera 40 from scratches and damage. The front shell 10 has an integrally formed physical light-blocking structure 107 between the infrared supplementary light source 30 and the infrared receiving camera 40. Its functions include: first, limiting the maximum emission angle θ3 of the infrared supplementary light source 30 (cutting off large-angle stray light) to prevent the light source from hitting the light-transmitting cover 202 at a large angle; second, blocking the direct beam transmission path between the infrared supplementary light source 30 and the infrared receiving camera 40 below the light-transmitting cover 202, thus structurally blocking the direct crosstalk path.

[0041] After optical simulation and multiple rounds of physical verification, taking into account factors such as the patch error and dimensional tolerance of optical components, the machining tolerance of the lock body, and the assembly error of the module and lock body structure, the minimum horizontal distance L between the points where the light emitted from the infrared supplementary light source 30 and the light incident from the infrared receiving camera 40 lands on the inner side of the light-transmitting cover plate 202 (near the front shell 10) must satisfy the following in the baseline plane: L≥7*t*tan(arcsin(sinθ3 / n)). Wherein, t is the thickness of the light-transmitting cover plate 202, n is the refractive index of the light-transmitting cover plate 202 for infrared light, and θ3 is the maximum emission angle of the infrared supplementary light source 30 towards the light-transmitting cover plate 202 (limited by the physical dimensions and position of the light-blocking structure 107).

[0042] Optionally, the infrared supplementary lighting source 30 includes an optical chip 32. Within the baseline plane of the infrared supplementary lighting source 30 and the infrared receiving camera 40, the minimum light emission angle θ2 of the infrared supplementary lighting source 30, defined by the light-blocking structure 107, satisfies: θ2≥arctan((d*tanθ0+Bs / 2) / D); Wherein, θ0 is the semi-mechanical field of view of the infrared receiving camera 40 on the side away from the infrared supplementary light source 30, B is the baseline distance between the optical axis of the infrared receiving camera 40 and the optical axis of the infrared supplementary light source 30, s is the width of the photochip 32 of the infrared supplementary light source 30 in the baseline direction, and D is the distance from the nearest measured object to the photochip. The semi-mechanical field of view θ0 can be understood as the half-field of view of the infrared receiving camera 40 on the side away from the infrared supplementary light source 30 in the baseline plane (i.e., the angle from the optical axis to the edge of the field of view); the baseline distance B can be understood as the horizontal distance between the optical axis of the infrared receiving camera 40 and the optical axis of the infrared supplementary light source 30; the photochip width s can be understood as the size of the photochip of the infrared supplementary light source 30 in the baseline direction; and the nearest measured object distance D can be understood as the shortest working distance that the 3D structured light module 100 can effectively identify.

[0043] Specifically, within the baseline plane, to ensure that the light emitted by the infrared supplementary light source 30 can completely cover the field of view of the infrared receiving camera 40 at the nearest measurement distance D, and to avoid dark edges appearing at the edges of the infrared image, the minimum emission angle θ2 of the infrared supplementary light source 30, defined by the light-blocking structure 107, should satisfy the above formula. The physical meaning of this formula is: at the nearest working distance D, the edge light rays of the infrared supplementary light source 30 on the side closest to the infrared receiving camera 40 (corresponding to the inner edge of the light source chip) must at least cover the edge position of the infrared receiving camera 40's field of view away from the light source (determined by d*tanθ0), taking into account the baseline offset B and the influence of the light source chip's half-width s / 2. When θ2 satisfies this condition, the illumination area of ​​the infrared supplementary light source 30 can completely cover the field of view of the infrared receiving camera 40 throughout the entire working distance range (from the nearest measurement distance D to the farthest measurement distance), ensuring that the acquired two-dimensional infrared image will not have dark edges or uneven brightness due to insufficient supplementary lighting. This ensures that the contours and texture features of targets such as faces and palms are clearly distinguishable, improving the accuracy and reliability of identity recognition. If θ2 is too small, the edge of the illumination spot of the infrared supplementary light source 30 cannot cover the edge of the field of view of the infrared receiving camera 40 at the closest measurement distance, resulting in insufficient brightness or complete darkness in the edge area of ​​the image.

[0044] Furthermore, under the premise of meeting the structural assembly requirements, in order to minimize the physical distance between the infrared supplementary light source 30 (infrared supplementary LED light source) and the infrared receiving camera 40, the baseline B and the minimum horizontal distance L have the following relationship. In the cross-section of the aforementioned terminal device 200, the distance from the center of the viewpoint of the infrared receiving camera 40 in the baseline direction field of view to the light-transmitting cover plate 202 is d1, and the distance from the light-emitting surface of the light chip 32 of the infrared supplementary light source 30 to the light-transmitting cover plate 202 is d2. Then the baseline distance B satisfies: B = d1 * tanθ1 + L + d2 * tanθ3, where θ1 is the half field of view of the infrared receiving camera 40 on the side of the baseline direction closer to the infrared supplementary light source 30, and θ3 is the maximum emission angle of the infrared supplementary light source 30 limited by the light-blocking structure 107 (i.e., the maximum emission angle of the chip edge of the infrared supplementary light source 30 on the side farther from the infrared receiving camera 40). At the same time, the minimum horizontal distance L also satisfies: L ≤ 9 * t * tan(arcsin(sinθ3 / n)).

[0045] Specifically, in the structural design, the baseline distance B consists of three parts: the projection width (d1*tanθ1) of the field of view boundary of the infrared receiving camera 40 on the inner side of the light-transmitting cover plate 202, the minimum horizontal distance L between the landing points of the two beams on the inner side of the cover plate (used to prevent crosstalk), and the projection width (d2*tanθ3) of the maximum emission angle θ3 of the infrared supplementary light source 30 on the inner side of the cover plate. In order to minimize the physical distance B within the limited structural space (to reduce the overall size of the module), the smallest possible value of L needs to be selected while meeting the crosstalk prevention conditions. Combining the aforementioned crosstalk prevention condition L≥7*t*tan(arcsin(sinθ3 / n)), and considering the engineering margin obtained from optical simulation and multiple rounds of physical verification, the minimum horizontal distance L simultaneously satisfies L≤9*t*tan(arcsin(sinθ3 / n)), that is, the value of L is between 7 and 9 times the constraint. Under the condition of satisfying the range of L values, the problem of light emitted by infrared supplementary light source 30 being directly transmitted into the field of view of infrared receiving camera 40 after being refracted by light-transmitting cover plate 202 can be effectively avoided. At the same time, it can ensure that the light in the effective light-emitting area of ​​the light source can be emitted without obstruction, completely covering the recognition field of view of infrared receiving camera 40, taking into account the requirements of anti-light transmission, supplementary light effect and module miniaturization.

[0046] Optionally, a light source raising block 31 may also be included; The infrared supplementary light source 30 is fixed to the circuit board 60 by the light source elevation block 31; Within the baseline plane of the infrared supplementary light source 30 and the infrared receiving camera 40, the first distance h1 between the top surface of the infrared supplementary light source 30 and the circuit board 60 is less than the second distance h2 between the top surface of the infrared receiving camera 40 and the circuit board 60, and the difference between the first distance h1 and the second distance h2 is 0~0.2mm.

[0047] Specifically, the 3D structured light module 100 also includes a light source elevation block 31. The infrared supplementary light source 30 is fixed to the circuit board 60 by the light source elevation block 31. In the baseline plane of the infrared supplementary light source 30 and the infrared receiving camera 40, the first distance h1 between the top surface (light-emitting surface) of the infrared supplementary light source 30 and the circuit board 60 is less than the second distance h2 between the top surface (lens front surface) of the infrared receiving camera 40 and the circuit board 60, and the difference between the first distance h1 and the second distance h2 (i.e., h2-h1) is 0~0.2mm (e.g., 0.1mm). By adjusting the height of the light source elevation block 31, the height difference between the light-emitting surface of the infrared supplementary light source 30 and the entrance pupil surface of the infrared receiving camera 40 in the Z-axis direction is controlled within 0.2mm, ensuring that the optical axes of the two are basically coplanar in the vertical direction. The purpose of this height-matching design is to reduce the window size of the area corresponding to the infrared supplementary light source 30 on the terminal device, thereby reducing the amount of external stray light entering through the window and preventing the light from the infrared supplementary light source 30 from directly shining obliquely onto the infrared receiving camera 40, further suppressing crosstalk. Simultaneously, this height difference range also takes into account the temperature rise that occurs when the infrared supplementary light source 30 is emitting light, and the sphere will expand slightly due to heat. The height difference between the infrared supplementary light source 30 and the lens provides deformation space, preventing the infrared supplementary light source 30 from making hard contact with the light-transmitting cover plate 202 after thermal expansion, avoiding glass breakage under pressure and damage to the infrared supplementary light source 30, and improving reliability in high and low temperature environments.

[0048] In one specific embodiment, the infrared supplementary light source 30 is a dual-junction infrared LED, and the image sensor in the infrared receiving camera 40 uses a global shutter chip solution. The dual-junction LED significantly improves the instantaneous peak luminous power compared to the single-junction LED: under the same pulse current drive, the light output power density of the dual-junction infrared LED is much higher than that of the single-junction LED, resulting in stronger short-time pulse lighting energy. In long-distance (e.g., 1m-2m) face recognition scenarios, sufficient supplementary lighting effectively improves the brightness and signal-to-noise ratio of infrared images under low light or long-distance conditions, ensuring a high recognition success rate. The global shutter sensor provides full-frame synchronous exposure, eliminating motion blur caused by rolling shutters: unlike the rolling shutter's line-by-line exposure method, the global shutter sensor starts and stops exposure simultaneously for all pixels, capturing instantaneous and complete motion images. This effectively avoids image distortion or blur caused by target (e.g., a walking person) movement. Even in dynamic pedestrian scenes, clear facial textures and speckle images can be acquired, ensuring the accuracy of depth calculation and feature recognition. The global shutter chip significantly reduces the exposure time required for the same image brightness: due to the higher photosensitivity and lower readout noise of the global shutter sensor, the exposure time required to achieve the same image brightness is much shorter than that of the rolling shutter solution.

[0049] Optionally, the front surface of the front housing 10 is provided with a speckle projector light emission clearance hole 102, an infrared supplementary light source light emission clearance hole 103, an infrared supplementary light source light emission clearance structure 105 and an infrared receiving camera light emission clearance hole 104 in sequence along the first direction x. The front shell 10 has a first end and a second end opposite each other in the second direction y, and the thickness of the front shell 10 gradually increases from the first end to the second end; The infrared supplementary light source emission obstruction structure 105 is disposed on the light-blocking structure 107 on the side of the infrared supplementary light source emission obstruction hole 103 near the infrared receiving camera emission obstruction hole 104, near the second end. Used to provide an unobstructed light path for the emitted light from the infrared supplementary light source 30, preventing the front cover 10 from blocking the supplementary light.

[0050] Specifically, the front surface 11 of the front housing 10 is sequentially provided with a speckle projector light-avoiding hole 102, an infrared supplementary light source light-avoiding hole 103, an infrared supplementary light source light-avoiding structure 105, and an infrared receiving camera light-avoiding hole 104 along the first direction x (baseline direction). The front housing 10 has a first end and a second end opposite to each other in the second direction y, and the thickness of the front housing 10 gradually increases from the first end to the second end (i.e., a preset tilt angle α is formed between the front surface 11 and the rear surface 12). The infrared supplementary light source light-avoiding structure 105 is disposed on the light-blocking structure 107 on the side of the infrared supplementary light source light-avoiding hole 103 near the infrared receiving camera light-avoiding hole 104, and near the second end (i.e., the end with greater thickness).

[0051] Because the thickness of the front shell 10 gradually increases from the first end to the second end (i.e., the front surface 11 is inclined), the emitted light from optical elements (such as the infrared supplementary light source 30) located near the second end may be partially blocked by the solid part of the front shell 10 due to the inclined front shell structure. To address this, an infrared supplementary light source emission avoidance structure 105 (e.g., a recess or chamfer) is provided on the side of the light-blocking structure 107 near the second end to provide an additional unobstructed light path for the emitted light from the infrared supplementary light source 30. This ensures that the light from the effective emitting area of ​​the infrared supplementary light source 30 can be projected onto the target area through the light-transmitting cover 202 without obstruction, completely covering the recognition field of view of the infrared receiving camera 40. Under the premise of reducing the distance between the infrared receiving camera 40 and the infrared supplementary light source 30 and compressing the width of the 3D structured light module 100, it ensures that the infrared supplementary light source 30's full-angle supplementary light is unobstructed by the shell, resulting in uniform brightness across the entire field of view of the face without any local dark areas.

[0052] Optionally, the edges of the speckle projector light emission clearance hole 102, the infrared supplementary light source light emission clearance hole 103, and the infrared receiving camera light emission clearance hole 104 are all provided with sealing adhesive grooves; the edge of the speckle projector light emission clearance hole 102 is provided with a speckle projector adhesive groove structure, the edge of the infrared supplementary light source light emission clearance hole 103 is provided with a light source adhesive groove structure, and the edge of the infrared receiving camera light emission clearance hole 104 is provided with an infrared camera adhesive groove structure; the sealing adhesive grooves are used to fill with sealant, so that a sealed connection is formed between the speckle projector light emission clearance hole 102 and the speckle projector 20, between the infrared supplementary light source light emission clearance hole 103 and the infrared supplementary light source 30, and between the infrared receiving camera light emission clearance hole 104 and the infrared receiving camera 40.

[0053] Specifically, during module assembly, after the speckle projector 20, infrared supplementary light source 30, and infrared receiving camera 40 are respectively aligned with their respective light emission clearance holes and installed on one side of the rear surface 12 of the front housing 10, sealant is injected into the corresponding sealing grooves through a dispensing needle. After the sealant cures, it fills the dispensing grooves and forms a tight bond with the outer wall of the optical device and the inner wall of the front housing 10. This creates a sealed connection between the speckle projector light emission clearance hole 102 and the speckle projector 20, between the infrared supplementary light source light emission clearance hole 103 and the infrared supplementary light source 30, and between the infrared receiving camera light emission clearance hole 104 and the infrared receiving camera 40. This blocks external environmental factors such as dust, water vapor, and insects from entering the module through the gaps between the optical device and the housing, preventing water vapor from condensing inside the transparent cover 202 and forming water mist, which would cause blurring of speckle and texture images. At the same time, the sealant also has a buffering and shock-absorbing function, protecting the optical chip and lens base and preventing assembly misalignment.

[0054] Figure 10 This is a side view cross-sectional diagram of a terminal device provided in an embodiment of the present invention. Figure 11 This is a schematic diagram of the rear view structure of a terminal device provided in an embodiment of the present invention. Figure 12 This is an exploded view of a terminal device provided in an embodiment of the present invention. (Reference) Figure 10-12 The present invention also provides a terminal device 200, which includes a smart door lock; The smart door lock includes a lock body shell, a light-transmitting cover plate 202, and a 3D structured light module 100 of any of the above embodiments; The lock body shell is the surface facing the user. The lock body shell has an opening, the position of which corresponds to the front shell 10 of the 3D structured light module 100. A light-transmitting cover plate 202 is installed on the opening. The front surface of the front shell 10 is parallel to the light-transmitting cover 202; The light-emitting side of the 3D structured light module 100 faces the light-transmitting cover plate 202.

[0055] Specifically, the terminal device 200 includes a smart lock. The smart lock includes a lock body shell, a light-transmitting cover plate 202, and a 3D structured light module 100 as described in any of the first aspects above. The lock body shell is the surface facing the user, and an opening is provided on the lock body shell. The position of the opening corresponds to the front shell 10 of the 3D structured light module 100, for embedding and fixing the module inside the lock body shell. A light-transmitting cover plate 202 is installed on the opening to protect the optical components inside the module. The front surface 11 of the front shell 10 is parallel to the light-transmitting cover plate 202 to ensure that the outgoing optical axis and receiving optical axis of the optical module are aligned with the normal direction of the cover plate, avoiding additional refraction and optical distortion caused by angular deviation. The light-emitting side of the 3D structured light module 100 faces the light-transmitting cover plate 202. The infrared speckle pattern emitted by the speckle projector 20 and the supplementary infrared light emitted by the infrared supplementary light source 30 pass through the light-transmitting cover plate 202 and illuminate the target area such as the user's face or palm. The infrared receiving camera 40 receives the reflected infrared light signal through the light-transmitting cover plate 202 to realize 3D depth perception and infrared image acquisition, thereby completing identity verification functions such as face recognition and liveness detection.

[0056] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A 3D structured light module, characterized in that, Installed on a terminal device, it includes a front shell and an optical module; the front shell includes a front surface and a rear surface that are disposed opposite to each other, and the front surface and the rear surface form a preset tilt angle; The optical module is mounted on one side of the rear surface of the front housing; The optical module includes a speckle projector, an infrared supplementary light source, an infrared receiving camera, and a circuit board; the speckle projector, the infrared supplementary light source, and the infrared receiving camera are all fixed on the circuit board; the infrared supplementary light source is arranged between the speckle projector and the infrared receiving camera; The preset tilt angle is 5°~15°.

2. The 3D structured light module according to claim 1, characterized in that, The front shell is also provided with positioning and locking holes. The positioning and locking hole structure includes a first fixing hole and a second fixing hole. The second fixing hole is used to engage with the positioning post on the terminal device to achieve pre-positioning. The first fixing hole is used for fasteners to pass through to fix the front shell and the terminal device.

3. The 3D structured light module according to claim 1, characterized in that, The speckle projector includes a diffractive optical element, wherein the vertical diffraction angle of the diffraction optical element is ≥100°, the depth processing tolerance is controlled within ±5%, and the overlay deviation is controlled within 100nm. The infrared receiving camera includes an infrared receiving lens, the vertical field of view of the infrared receiving lens is ≥100°, and the overall optical distortion of the infrared receiving lens is ≤2%.

4. The 3D structured light module according to claim 1, characterized in that, The terminal device has an opening on its surface facing the user, the opening being positioned opposite the front shell, and a light-transmitting cover is installed on the opening. The thickness of the light-transmitting cover is t, and its refractive index for infrared light is n. The front surface of the front shell is parallel to the light-transmitting cover plate; The front cover also includes a light-blocking structure, which is located between the infrared supplementary light source and the infrared receiving camera. The light-blocking structure is used to limit the maximum emission angle θ3 of the infrared supplementary light source towards the light-transmitting cover plate, and to block the direct beam transmission path between the infrared supplementary light source and the infrared receiving camera below the light-transmitting cover plate. Within the baseline plane of the infrared supplementary light source and the infrared receiving camera, the minimum horizontal distance L between the points where the light emitted from the infrared supplementary light source and the light incident from the infrared receiving camera lands on the side of the light-transmitting cover closest to the front shell satisfies: L≥7*t*tan(arcsin(sinθ3 / n)).

5. The 3D structured light module according to claim 4, characterized in that, The minimum horizontal spacing L satisfies: L≤9*t*tan(arcsin(sinθ3 / n)).

6. The 3D structured light module according to claim 4, characterized in that, The infrared supplementary light source includes an optical chip. Within the baseline plane of the infrared supplementary light source and the infrared receiving camera, the minimum light emission angle θ2 of the infrared supplementary light source, defined by the light-blocking structure, satisfies: θ2≥arctan((d*tanθ0+Bs / 2) / D); Wherein, θ0 is the semi-mechanical field of view angle of the infrared receiving camera on the side away from the infrared supplementary light source, B is the baseline distance between the optical axis of the infrared receiving camera and the optical axis of the infrared supplementary light source, s is the width of the optical chip of the infrared supplementary light source in the baseline direction, d is the distance from the center of the viewpoint of the infrared receiving camera in the baseline direction to the light-transmitting cover plate, and D is the distance from the nearest measured object to the optical chip.

7. The 3D structured light module according to claim 4, characterized in that, It also includes light source shims; The infrared supplementary light source is fixed to the circuit board by the light source elevation block; Within the baseline plane of the infrared supplementary light source and the infrared receiving camera, the first distance between the top surface of the infrared supplementary light source and the circuit board is less than the second distance between the top surface of the infrared receiving camera and the circuit board, and the difference between the first distance and the second distance is 0~0.2mm.

8. The 3D structured light module according to claim 4, characterized in that, The front surface of the front shell is provided with a speckle projector light emission avoidance hole, an infrared supplementary light source light emission avoidance hole, an infrared supplementary light source light emission avoidance groove and an infrared receiving camera light emission avoidance hole in sequence along the first direction. The front shell has a first end and a second end opposite each other in a second direction, and the thickness of the front shell gradually increases from the first end to the second end; The infrared supplementary light source emission clearance slot is disposed on the light-blocking structure on the side of the infrared supplementary light source emission clearance hole near the infrared receiving camera emission clearance hole, near the second end. This is used to provide an unobstructed optical path for the emitted light from the infrared supplementary light source, thereby preventing the front shell from blocking the supplementary light.

9. The 3D structured light module according to claim 5, characterized in that, The edges of the light emission clearance holes of the speckle projector, the infrared supplementary light source, and the infrared receiving camera are all provided with sealing adhesive grooves; the sealing adhesive grooves are used to fill the grooves with sealant to form a sealed connection between the light emission clearance hole of the speckle projector and the speckle projector, between the light emission clearance hole of the infrared supplementary light source and the infrared supplementary light source, and between the light emission clearance hole of the infrared receiving camera and the infrared receiving camera.

10. A terminal device, characterized in that, The terminal device includes a smart door lock; The smart door lock includes a lock body shell, a light-transmitting cover plate, and a 3D structured light module as described in any one of claims 1 to 9; The lock body shell has a surface facing the user, and an opening is provided on the surface of the lock body shell facing the user. The position of the opening corresponds to the front shell of the 3D structured light module, and a light-transmitting cover is installed on the opening. The surface of the lock body shell facing the user is parallel to the light-transmitting cover plate; The light-emitting side of the 3D structured light module faces the light-transmitting cover plate.

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