A biometric device based on a surface light source

Abstract

A biometric identification device based on a surface light source is characterized by comprising: a housing including a light-emitting surface; a sensor located inside the housing for receiving reflected signals from a palm or face; multiple lateral light sources located inside the housing, emitting active light towards a center point; the center point being the center of a shape formed by the multiple lateral light sources; a light guide plate located on the light path of the lateral light sources illuminating the center point, for causing the active light to exit from the side; and a light-diffusing plate located above the light guide plate to ensure uniform emission of the active light. This invention utilizes lateral light sources illuminating along the light guide plate and a light-diffusing plate to ensure uniform emitted light, resulting in a more uniform light path, lower cost, fewer control components, and is beneficial for large-scale applications.

Description

Technical Field

[0001] This utility model relates to the field of biometric technology, specifically to a biometric device based on a surface light source. Background Technology

[0002] Surface light sources play a crucial role in biometric technology, especially in facial recognition. They have the following important functions:

[0003] Providing stable illumination: In biometric identification, changes in external lighting can significantly affect recognition results. Surface light sources provide a stable and uniform lighting environment, reducing the impact of lighting variations on human image quality, thereby improving the accuracy and stability of identification.

[0004] Enhanced image quality: Surface light sources can illuminate various parts of the human body, reducing shadows and reflections, making human body images clearer and more detailed, which is beneficial for the accurate processing of human body recognition algorithms.

[0005] Supports multiple application scenarios: Lighting conditions vary greatly in different scenarios, and surface light sources can be adjusted according to specific needs to adapt to the recognition requirements of different scenarios. For example, in backlight, front lighting, or low-light environments, surface light sources can provide appropriate lighting compensation to ensure smooth face recognition.

[0006] A surface light source mainly consists of a light source, a panel, and auxiliary components. The light source is the core component of the surface light source, and it generally uses LED chips or cold cathode fluorescent lamps. These light sources have good luminous efficacy, long lifespan, and high energy efficiency, making them suitable for long-term continuous operation. The panel is used to evenly distribute the light emitted by the light source to achieve a uniform overall illumination effect.

[0007] In traditional lighting systems, achieving uniform illumination typically requires the use of large-area light sources or complex optical systems. These systems are often costly and struggle to achieve ideal lighting results in certain applications.

[0008] The above background information is provided only to aid in understanding the inventive concept and technical solution of this utility model. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Utility Model Content

[0009] Therefore, this invention uses a side light source to illuminate the light guide plate and a light homogenizing plate to make the emitted light uniform, resulting in a more uniform light path. It is also low in cost, simple in structure, and requires fewer control devices, which is conducive to large-scale application.

[0010] This utility model provides a biometric identification device based on a surface light source, characterized in that it includes:

[0011] The housing includes a light-emitting surface;

[0012] A sensor, located inside the housing, is used to receive reflected signals from a palm or face;

[0013] Multiple side light sources are located inside the housing and emit active light toward a center point; the center point is the center of the shape formed by the multiple side light sources.

[0014] A light guide plate is located on the light path of the side light source pointing to the center point, and is used to make the active light exit from the side;

[0015] A light-diffusing plate is located above the light guide plate to ensure that the active light is emitted uniformly.

[0016] Optionally, the biometric device based on a surface light source is characterized in that the lateral light source is arranged symmetrically about the center point.

[0017] Optionally, the biometric device based on a surface light source is characterized in that the light guide plate has a reflective portion at one end near the center point, for reflecting the remaining light to the light uniform plate.

[0018] Optionally, the biometric device based on a surface light source is characterized in that an emission section is provided above the light guide plate for emitting light at a certain emission ratio; and a downwardly protruding total reflection section is provided below the light guide plate for reflecting light upward at a specific angle.

[0019] Optionally, the biometric device based on a surface light source is characterized in that the emission portion has a higher emission ratio the closer it is to the center point.

[0020] Optionally, the biometric device based on a surface light source is characterized in that a light-transmitting hole is provided in the center of the light-diffusing plate so that the sensor can receive light signals.

[0021] Optionally, the biometric device based on a surface light source is characterized in that a blocking component is provided above the sensor along the optical path direction to block stray light from entering the sensor.

[0022] Optionally, the biometric device based on a surface light source is characterized in that the included angle between adjacent light guide plates is negatively correlated with the light attenuation rate in the light guide plates.

[0023] Optionally, the biometric device based on a surface light source is characterized in that the haze is lower in the portion of the light-diffusing plate closer to the center.

[0024] Optionally, the biometric device based on a surface light source is characterized in that the housing includes a first step and a second step; the first step is fixedly connected to a transparent cover plate, and the second step is fixedly connected to the light-diffusing plate; the first step is higher than the second step, and the first step is farther from the center of the light-diffusing plate than the second step.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention utilizes a side-emitting light source that illuminates a light-diffusing plate from multiple points via a light guide plate. After modulation by the light-diffusing plate, the light path becomes more uniform and the light is softer, resulting in higher-quality images of hands or faces. Simultaneously, the side-emitting light source reduces the amount of light source data, lowering control complexity and cost, and providing a more effective illumination range for palm or face scanning applications. This invention features a simple structure, low cost, and ease of installation and maintenance. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. Other features, objects, and advantages of this utility model will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0028] Figure 1 This is a schematic diagram of the structure of a biometric device based on a surface light source in an embodiment of this utility model;

[0029] Figure 2 This is a schematic diagram of an optical path in an embodiment of the present invention;

[0030] Figure 3 This is a schematic cross-sectional view of a light guide plate in one embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the structure of a light-transmitting hole in an embodiment of this utility model;

[0032] Figure 5 This is a schematic diagram of the structure of a transparent cover plate in an embodiment of this utility model.

[0033] 1-Shell;

[0034] 2-Side light source;

[0035] 3-Light guide plate;

[0036] 4-Light homogenizer;

[0037] 5-Sensors;

[0038] 6-Reflective part;

[0039] 7-Exit part;

[0040] 8-Total reflective part;

[0041] 9-Light transmission hole;

[0042] 10 - Light-blocking layer;

[0043] 11-Barrier components;

[0044] 12- Transparent cover;

[0045] 13 - First step;

[0046] 14 - Second step; Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0048] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the utility model described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0049] This utility model provides a biometric device based on a surface light source, which aims to solve the problems existing in the prior art.

[0050] The technical solutions of this utility model and this application solve the above-mentioned technical problems in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this utility model will now be described with reference to the accompanying drawings.

[0051] This invention uses a side light source to illuminate the light guide plate and a light homogenizing plate to make the emitted light uniform, resulting in a more uniform light path. It is also low in cost and requires fewer control devices, which is beneficial for large-scale applications.

[0052] Figure 1 This is a schematic diagram of the structure of a biometric device based on a surface light source according to an embodiment of this utility model. Figure 1 As shown, an embodiment of this utility model of a biometric device based on a surface light source includes:

[0053] Housing 1 includes a light-emitting surface.

[0054] Specifically, housing 1 is used to house and protect internal components, such as side light sources, light guide plates, light doubling plates, and sensors. The housing can be of various shapes, such as cuboids or cylinders. One surface of the housing has an opening, the light-emitting surface, for light to pass through and capture images of a hand or face. The housing is generally made of robust and durable materials, such as metal or high-strength plastic, to resist external impacts and prevent damage to internal components. The housing design should consider heat dissipation requirements to ensure the stability of the module during long-term operation.

[0055] Sensor 5, located inside the housing, is used to receive reflected signals from a palm or face.

[0056] Specifically, the sensor can be an infrared sensor or other types of optical sensors used to capture reflected light from the palm or face and convert it into a digital image. This is one of the core components of palm recognition technology. The sensor typically employs a high-sensitivity image sensor, such as CMOS or CCD. When sensor 3 is a visible light sensor, it can acquire the texture features of the palm or face surface; when sensor 3 is an infrared sensor, it can acquire the vascular features of the palm or face epidermis. Both the texture and vascular features of the palm or face can be used for liveness detection and identity authentication. The type and number of sensors need to match the side light source. When the side light source 2 is a visible light side light source, sensor 3 is a visible light sensor. When the side light source 2 is an infrared side light source, sensor 3 is an infrared sensor. When there are two or more side light sources 2 of different types, the number of sensors 3 is also two or more of different types. It should be noted that the number of side light sources 2 and the number of sensors 3 are not always the same.

[0057] Multiple side light sources 2 are located inside the housing and emit active light toward a center point; the center point is the center of the shape formed by the multiple side light sources.

[0058] Specifically, the side light source 2 can be an infrared light source, visible light, or other types of light source, used to provide sufficient light to illuminate an image of a hand or face. The side light source typically includes components such as a light source and lenses, capable of producing pre-designed light. Active light is collimated light, making its transmission within the light guide plate controllable. The number of side light sources can be one, two, three, or more. When there are two or more side light sources, the types of side light sources can be different; for example, one can be an infrared side light source, and another a visible light side light source. The side light sources can be any type of light source, such as LED light sources, metal halide lamp light sources, or infrared light sources.

[0059] In some embodiments, the lateral light source includes: a light-emitting diode (LED) as the light source; and an optical lens for focusing and directing the light emitted by the LED. This embodiment has lower cost and higher reliability, which is beneficial for large-scale industrial applications.

[0060] The light guide plate 3 is located on the light path of the side light source hitting the center point, and is used to make the active light emit from the side.

[0061] Specifically, the light guide plate is used to receive active light emitted from a side-mounted light source and, through its internal structural design (such as light guide points and microstructures), uniformly guides the light to the light-emitting surface. The light guide plate utilizes the principle of total internal reflection to guide light from one side to the other, and its microstructure design ensures uniform light distribution on the light-emitting surface. The light guide plate improves light utilization efficiency, allowing light to be fully utilized within the module and reducing light loss.

[0062] A light-diffusing plate 4 is located above the light guide plate to ensure that the active light is emitted uniformly.

[0063] Specifically, the light homogenizing plate, located above the light guide plate, is responsible for further homogenizing the light emitted from the light guide plate, ensuring that the light emitted from the light-emitting surface is uniform and spotless. The light passing through the light homogenizing plate will be evenly emitted to the palm or face, ensuring that the sensor can receive a uniform and consistent reflected light signal, which is crucial for improving the accuracy of biometric recognition. Figure 1 The location of the light-diffusing plate is not marked in the image; please refer to [reference needed]. Figure 2 .

[0064] In some embodiments, a biometric device based on a surface light source further includes a control unit for adjusting the brightness and on / off state of the side light source unit. The control unit can adjust the brightness and on / off state of the side light source via current or voltage signals, thereby enabling different illumination states in this embodiment. The control unit includes: a brightness adjustment module for adjusting the brightness of the side light source unit according to supplemental lighting needs; and an on / off control module for controlling the opening and closing of the side light source unit. Through the adjustment of the control unit, the light intensity can be flexibly adjusted according to actual needs.

[0065] In some embodiments, a biometric device based on a surface light source further includes a sensor unit for detecting the illumination intensity of the supplementary lighting space and feeding it back to the control unit for brightness adjustment. The addition of the sensor unit improves the system's intelligence level and enables automatic adjustment.

[0066] Figure 2 This is a schematic diagram of an optical path according to an embodiment of the present invention. Figure 2 As can be seen, the active light emitted from the side light source 2 enters the light guide plate 3. The light propagates continuously towards the center point within the light guide plate 3, and during the propagation process, a portion of the light exits from above. The light exiting from above illuminates the light homogenizing plate 4, and then finally exits.

[0067] In some embodiments, the lateral light sources are arranged symmetrically about the center point. The use of multiple light guide plates can further refine the light distribution and ensure the uniformity of light across the entire light-emitting surface. Multiple light guide plates result in a relatively uniform light distribution on the light-emitting surface, and after treatment with a light homogenizer, the light emitted from the light-emitting surface is even more uniform.

[0068] In some embodiments, such as Figure 4As shown, the light guide plate has a reflective portion 6 at one end near the center point, used to reflect residual light to the light homogenizing plate. In the design of the light guide plate, if a reflective portion is added at the central end, the main function of this reflective portion is to reflect the residual light that has not been fully utilized or has not yet reached the light-emitting surface during its propagation inside the light guide plate, so that it can be redirected and evenly distributed on the light homogenizing plate. This design further improves the light utilization rate and the light uniformity of the light-emitting surface. It should be noted that, in order to avoid excessive light intensity in the center due to the reflection of light from multiple light guide plates, the reflective portion needs to process the reflection angle of the light so that the reflected light is more evenly distributed above the light homogenizing plate. The reflective portion is usually made of a high-reflectivity material, such as a mirror material or a specially coated plastic / metal, to ensure that the light can be effectively reflected back into the light guide plate or guided to the light homogenizing plate. This embodiment allows the reuse of residual light that might otherwise be wasted, thereby improving the light utilization rate of the entire module. Through the reflection of the reflector, the light that might have been concentrated in certain areas of the light guide plate is dispersed to a wider area, further enhancing the uniformity of light on the light-emitting surface.

[0069] In some embodiments, such as Figure 3As shown, an emitting section 7 is located above the light guide plate, used to emit light at a certain emission ratio; a downwardly protruding total internal reflection section 8 is located below the light guide plate, used to reflect light upwards at a specific angle. The emitting section located above the light guide plate is crucial in its microstructure, which adjusts the emission ratio. When light enters the light guide plate from its light source inlet (e.g., side or bottom), it undergoes multiple reflections and refractions within the plate. Upon reaching the microstructure of the emitting section, a portion of the light is redirected and emitted from the front of the light guide plate. By precisely designing the shape, size, and density of these microstructures, the emission ratio can be controlled, thus affecting the brightness and uniformity of the entire light-emitting surface. Specifically, these microstructures can be microlens arrays, prism structures, or other shapes with scattering capabilities, which can disrupt the total internal reflection conditions within the light guide plate, causing the light to emit from the front with a specific direction and intensity. The emitting section has a higher emission ratio closer to the center point. Below the light guide plate is a downward-protruding total internal reflection section. This section, through its geometry and optical design, reflects light that hasn't escaped from the exit section back into the light guide plate. This protruding structure is typically designed with a curved or inclined surface, allowing light to be reflected according to the principle of "total internal reflection" when it hits this section. Specifically, total internal reflection means that when light travels from a high-refractive-index medium (such as the acrylic material of the light guide plate) to a low-refractive-index medium (such as air), if the angle of incidence is greater than a certain critical angle, the light will not be refracted out of the medium but will be completely reflected back inside. By precisely designing the tilt angle and surface characteristics of this protruding structure, it is ensured that as much light as possible is effectively reflected, continues to propagate within the light guide plate, and ultimately exits from the exit section. Through the precise design and coordinated operation of these two parts, the light guide plate can efficiently conduct and control light, achieving high-quality surface light source illumination. This design not only improves lighting effects and energy efficiency but also greatly expands the flexibility and applicability of the light guide plate in various application scenarios.

[0070] In some embodiments, such as Figure 4As shown, a light-diffusing plate has a central light-passing hole 9 to allow the sensor to receive light signals passing through it. The light-passing hole provides a direct path for light to travel from above to below the light-diffusing plate. When a hand or face is above the module, the light reflected from the hand or face passes through the light-passing hole to reach the sensor. The position of the light-passing hole corresponds to the receiving area of ​​the sensor to ensure that the sensor can accurately receive light from specific areas of the hand or face. The light-passing hole can be flush with or higher than the sensor. When the light-passing hole is flush with the sensor, the thickness of the palm-scanning module can be minimized. This design helps improve the accuracy and stability of recognition. When a hand or face is above the module, it reflects light from the light-diffusing plate. These reflected rays pass through the light-passing hole and reach the sensor. The sensor receives and analyzes these light signals to identify the characteristic information of the hand or face (such as palm prints, blood vessel distribution, etc.).

[0071] In some embodiments, such as Figure 4 As shown, a light-blocking layer 10 is provided on the side of the light-transmitting aperture to prevent light from shining from the light-diffusing plate onto the sensor. The setting of the light-transmitting aperture and the use of the light-blocking layer are key factors in ensuring light transmission efficiency and preventing light crosstalk. The light-blocking layer is mainly used to prevent light crosstalk between different optical areas, ensuring that light propagates along the expected path. The light-blocking layer is usually made of materials with high absorbency or high reflectivity, such as black light-absorbing materials or metal reflective films. These materials can effectively absorb or reflect light, preventing it from penetrating to the sensor. The structural design of the light-blocking layer needs to consider its fit with the light-transmitting aperture and the optical performance of the entire module. It should fit tightly against the side of the light-transmitting aperture without affecting the normal transmission of light or the sensor's receiving angle. Located on the side of the light-transmitting aperture, the light-blocking layer acts like a barrier, blocking light from other areas of the light-diffusing plate, ensuring the purity and accuracy of the optical signal, and enhancing the recognition effect.

[0072] In some embodiments, such as Figure 4 As shown, a blocking component 11 is disposed above the sensor along the optical path direction to block stray light from entering the sensor. The blocking component is made of opaque material and is used to block light from below the light-diffusing plate from entering the sensor. One end of the blocking component is connected to the sensor, and the other end is connected to the light-diffusing plate, thereby blocking light reflected from the light-diffusing plate and light emitted from the light guide plate from entering the sensor.

[0073] In some embodiments, the angle between adjacent light guide plates is negatively correlated with the light attenuation rate within the light guide plate. The light guide plate is elongated. When multiple light guide plates are present, they are located on the same plane, with an angle between adjacent light guide plates. Different light guide plate designs result in different light attenuation rates. The faster the light attenuation rate of a light guide plate, the weaker the light intensity emitted from the central end of the light guide plate, leading to a lower light intensity in the center of the light homogenizer. Therefore, the greater the light attenuation rate of a light guide plate, the more light guide plates are needed to maintain a strong light intensity in the center; in this case, the angle between adjacent light guide plates is smaller.

[0074] In some embodiments, the haze is lower closer to the center of the light-diffusing plate. Haze is an indicator of a material's ability to scatter light; it reflects the degree to which light is scattered within or on the surface of the material. In a light-diffusing plate, appropriate haze helps to homogenize light, creating a soft and uniform illumination effect on the plate surface. However, excessive haze can also lead to overly scattered light, affecting light transmission efficiency and recognition accuracy. Because the light-diffusing plates are arranged around the center, for the same area, there are more light-diffusing plates in the center than at the edges, resulting in a more uniform light distribution, but at the same time, the brightness of each light-diffusing plate is lower. This embodiment designs the portion of the light-diffusing plate closer to the center to have lower haze while also having higher transmittance. This helps to reduce light scattering in this area, resulting in higher intensity light emitted through the light-diffusing plate. In contrast, the edge portions of the light-diffusing plate are designed with higher haze. This is to utilize the scattering effect to evenly distribute light from the light source (such as an LED) across the entire plate surface. By increasing the haze in the edge areas, the light can gradually diffuse during transmission, creating a uniform illumination effect. This embodiment helps to achieve uniform light distribution across the entire light-diffusing plate, ensuring consistent lighting conditions regardless of where the hand or face is located on the module.

[0075] In some embodiments, such as Figure 5 As shown, the housing includes a first step 13 and a second step 14; the first step is fixedly connected to the transparent cover plate 12, and the second step is fixedly connected to the light-diffusing plate; the first step is higher than the second step, and the first step is farther from the center of the light-diffusing plate than the second step. The transparent cover plate can prevent physical damage and scratches. The transparent cover plate needs to have good light transmittance to ensure that light can pass smoothly through and illuminate the surface of the palm or face. Figure 5As shown, the first step is located at the top of the housing and is fixedly connected to the transparent cover plate. Since the first step is higher than the second step and farther from the center of the light-diffusing plate, it primarily provides a stable support platform for the transparent cover plate. This design helps ensure a certain distance between the transparent cover plate and the light-diffusing plate, preventing abrasion or pressure that might occur from direct contact from being transmitted to the light-diffusing plate. The second step is located below the first step and is fixedly connected to the light-diffusing plate. The second step directly supports the light-diffusing plate, ensuring its stability and positional accuracy. Because the second step is closer to the center of the light-diffusing plate than the first step, it can more effectively transmit light from the array's side light sources, reducing light loss and scattering during transmission. The first step's greater distance from the center of the light-diffusing plate compared to the second step helps to better control light propagation. For example, in applications where it is necessary to avoid direct central light shining onto the transparent cover plate causing reflections or glare, this design can effectively guide light to scatter in all directions, thereby reducing unwanted light effects.

[0076] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to implement or use this invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this invention. Therefore, this invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0077] The specific embodiments of this utility model have been described above. It should be understood that this utility model is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this utility model.

Claims

1. A biometric identification device based on a surface light source, characterized in that, include: The housing includes a light-emitting surface; A sensor, located inside the housing, is used to receive reflected signals from a palm or face; Multiple side light sources are located inside the housing and emit active light toward a center point; the center point is the center of the shape formed by the multiple side light sources. A light guide plate is located on the light path of the side light source pointing to the center point, and is used to make the active light exit from the side; A light-diffusing plate is located above the light guide plate to ensure that the active light is emitted uniformly. The light guide plate has an emission section above it for emitting light at a certain emission ratio; the light guide plate has a downward-protruding total reflection section below it for reflecting light upward at a specific angle.

2. The biometric identification device based on a surface light source according to claim 1, characterized in that, The side light sources are arranged symmetrically about the center point.

3. The biometric identification device based on a surface light source according to claim 1, characterized in that, The light guide plate has a reflective portion at one end near the center point, which is used to reflect the remaining light to the light uniform plate.

4. A biometric identification device based on a surface light source according to claim 1, characterized in that, The closer the emission section is to the center point, the higher its emission ratio.

5. A biometric identification device based on a surface light source according to claim 1, characterized in that, The light-diffusing plate has a light-transmitting hole in the center so that the sensor can receive light signals.

6. A biometric identification device based on a surface light source according to claim 1, characterized in that, A blocking component is provided above the sensor along the optical path to block stray light from entering the sensor.

7. A biometric identification device based on a surface light source according to claim 2, characterized in that, The included angle between adjacent light guide plates is negatively correlated with the light attenuation rate in the light guide plate.

8. A biometric device based on a surface light source according to claim 2, characterized in that, The closer the light-diffusing plate is to the center, the lower the haze.

9. A biometric identification device based on a surface light source according to claim 1, characterized in that, The housing includes a first step and a second step; the first step is fixedly connected to a transparent cover plate, and the second step is fixedly connected to the light-diffusing plate; the first step is higher than the second step, and the first step is farther from the center of the light-diffusing plate than the second step.

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