Spherical brush palm module

Abstract

A spherical brush palm module is characterized by comprising an LED light source used for projecting light; the receiver is positioned in the middle of the LED light source and is used for receiving a reflected signal of the light; the spherical cover is positioned on a light path of the light rays and is used for uniformly emitting the light rays; and the center of the spherical cover is transparent, so that the light rays penetrate and irradiate the receiver. The spherical cover is adopted to process the light path, so that the light path is more matched with the characteristics of the palm surface, the palm can be irradiated more uniformly, meanwhile, the center of the spherical cover is transparent, and the spherical cover is matched with the palm, so that the environmental interference can be reduced, and the anti-interference capability is obviously enhanced.

Description

Technical Field

[0001] This utility model relates to the field of palm brush module technology, specifically to a spherical palm brush module. Background Technology

[0002] With the rapid development of biometric technology, contactless palmprint and palm vein recognition systems have gradually become mainstream due to their high security and convenience. Traditional palm-swipe modules typically use a planar light source in conjunction with an image sensor, but this approach has significant drawbacks in practical applications:

[0003] Insufficient uniformity of light: Due to the limited incident angle, the illumination of the edge area of ​​the palm is reduced by the planar light source, which causes shadow interference, especially when recognizing curved palms, and affects the accuracy of feature point extraction.

[0004] Severe signal crosstalk: When the transmitting light source and receiver are arranged side by side, stray light from the environment can easily enter the receiver directly, causing a decrease in the signal-to-noise ratio (SNR);

[0005] High structural redundancy: Existing modules often require the addition of multiple layers of optical components such as light guide plates and diffusion films to compensate for optical path losses, resulting in increased device thickness and making it difficult to meet the miniaturization requirements of scenarios such as smart door locks;

[0006] Dynamic recognition defects: Single-band light sources are prone to loss of feature information under complex working conditions such as wet palms and dirt, which reduces the robustness of recognition.

[0007] Industry attempts have attempted to improve this through ring light sources or multispectral imaging, but the following bottlenecks remain:

[0008] Although the central receiver layout of the ring light source shortens the optical path, the distribution of point light sources will still produce bright and dark stripes.

[0009] Multispectral systems rely on complex spectroscopic filtering devices, which significantly increases manufacturing costs and optical calibration difficulties.

[0010] 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

[0011] Therefore, this invention uses a spherical mask to process the light path, making the light path more compatible with the characteristics of the palm and allowing for more uniform illumination of the palm. At the same time, the center of the spherical mask is transparent, which, together with the palm, can reduce environmental interference and significantly enhance the anti-interference ability.

[0012] This utility model provides a spherical brush palm module, characterized in that it includes:

[0013] LED light source, used to project light;

[0014] A receiver, located in the middle of the LED light source, receives the reflected signal of the light.

[0015] A spherical mask, located in the optical path of the light beam, is used to uniformly emit the light beam;

[0016] The center of the spherical cover is transparent, allowing the light to pass through and illuminate the receiver.

[0017] Optionally, the spherical brush palm module is characterized in that the LED light source includes at least three sub-light sources evenly distributed around the receiver.

[0018] Optionally, the spherical brush module is characterized in that the sub-light source is installed facing outward at a 30° tilt angle, and the central axis of the light source coincides with the curvature center of the spherical mask.

[0019] Optionally, the spherical brush palm module is characterized in that the LED light source emits at least two different types of light.

[0020] Optionally, the spherical brush palm module is characterized in that the spherical cover includes at least two different phosphors and emits light under at least two different light sources.

[0021] Optionally, the spherical brush palm module is characterized in that the different phosphors form different patterns.

[0022] Optionally, the spherical brush module is characterized in that the two different rays are polarized light with a 90° phase difference, and the receiver is equipped with a corresponding polarization filter.

[0023] Optionally, the spherical brush palm module is characterized in that the LED light source comprises a combination of infrared light with a wavelength range of 850-940nm and visible light with a wavelength range of 450-550nm.

[0024] Optionally, the spherical brush palm module is characterized in that the outer surface of the spherical cover is provided with a microprism array and the inner surface is coated with an anti-reflection film.

[0025] Optionally, the spherical brush module is characterized in that the transparent area of ​​the spherical cover is provided with a Fresnel lens structure for focusing the reflected signal to the photosensitive surface of the receiver.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This utility model's spherical cover converts LED point light sources into uniform surface light sources, eliminating the corner attenuation effect of traditional planar light sources and matching the anatomical features of the curved surface of the palm.

[0028] The receiver of this invention is embedded in the center of the LED light source array, and together with the transparent area of ​​the spherical cover, a coaxial optical path for transmission and reception is established, which effectively suppresses ambient light interference.

[0029] This invention uses a single-piece spherical cover to replace the traditional multi-layer optical structure, reducing the module thickness to less than 8mm, thus meeting the embedded installation requirements of smart terminals. Attached Figure Description

[0030] 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:

[0031] Figure 1 This is a schematic diagram of the structure of a spherical brush palm module in an embodiment of this utility model;

[0032] Figure 2 This is a schematic diagram of a fluorescent powder pattern in an embodiment of the present invention.

[0033] 1-LED light source;

[0034] 2- Receiver;

[0035] 3-Spherical mask;

[0036] 4-Center transparent area; Detailed Implementation

[0037] 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.

[0038] 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.

[0039] This utility model provides a spherical brush palm module, which aims to solve the problems existing in the prior art.

[0040] 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.

[0041] like Figure 1 As shown, in this embodiment of the present invention, a spherical brush palm module includes:

[0042] LED light source 1, used to project light;

[0043] Receiver 2, located in the middle of the LED light source, receives the reflected signal of the light;

[0044] The spherical mask 3 is located in the optical path of the light beam and is used to uniformly emit the light beam;

[0045] The center of the spherical cover is transparent, allowing the light to pass through and illuminate the receiver.

[0046] Specifically, the LED light source employs a multi-band LED array, typically combining near-infrared (850–940 nm) and visible light (such as 450 nm blue light or 520 nm green light). Near-infrared light is used to capture subcutaneous vein features, while visible light is used for palm print surface detail recognition. The LEDs are arranged in a tightly packed ring array, symmetrically distributed around the receiver (e.g., 6–8 LEDs spaced at equal angles), ensuring uniform 360° illumination. An integrated constant current driver chip supports pulse modulation (e.g., 10 kHz frequency), reducing multispectral interference by emitting different wavelengths of light in a time-division manner. Near-infrared LEDs penetrate biological tissue to 3–5 mm, with venous hemoglobin showing significantly higher absorption rates than surrounding tissues; blue LEDs excite reflection from the stratum corneum of the palm surface, enhancing texture contrast. Timing control enables layered acquisition of vein and palm print information, avoiding signal aliasing. Power consumption under pulse drive is less than 200 mW, meeting the battery life requirements of embedded devices.

[0047] The receiver employs a global shutter CMOS image sensor (e.g., 1 / 2.8 inch, 1280×1024 effective pixels) and supports near-infrared enhancement mode (quantum efficiency > 40% @ 850nm). The photosensitive surface faces the central transparent area of ​​the spherical mask, forming a coaxial optical path (the emission and reception optical paths coincide), which suppresses oblique stray light interference to the greatest extent.

[0048] It integrates HDR algorithms to fuse images with different exposure times within a single frame, adapting to the brightness differences between the palm and the background (e.g., 100dB dynamic range).

[0049] A thermally conductive silicone pad is attached to the back of the sensor to conduct heat to the metal bracket, ensuring that the operating temperature remains below 50°C for extended periods. The optical window features a nano-oleophobic coating and is surrounded by a rubber sealing ring, achieving an IP67 protection rating.

[0050] The substrate of the spherical mask is made of optical-grade PMMA (transmittance ≥92%) or polycarbonate (impact-resistant), and the surface is precisely spherical (radius of curvature R = 15mm ± 0.1mm) by diamond turning. The outer surface of the spherical mask uses an etched microprism structure (unit size 50μm × 50μm) to convert the LED point light source into uniform Lambertian emitted light, with an illuminance uniformity >90%. The inner surface of the spherical mask is coated with an antireflective coating (AR coating), with an average reflectivity of <0.5% in the 850nm and 450nm wavelength bands.

[0051] The peripheral area of ​​the spherical mask contains diffusing particles (such as titanium dioxide nanoparticles, concentration 0.5wt%) to achieve light softening and uniform scattering. The central transparent area of ​​the spherical mask is a high-transmittance region with a diameter of 8mm (haze <1%), with a built-in Fresnel lens structure to focus reflected light onto the photosensitive surface of the receiver, increasing light energy utilization to over 85%.

[0052] The spherical cover features a snap-fit ​​groove along its edge, ensuring an interference fit with the module housing and maintaining an installation tolerance within ±0.05mm to guarantee optical path alignment. The surface of the spherical cover is coated with an anti-fingerprint coating (contact angle >110°) to reduce the impact of oil and dirt adhesion on light transmittance.

[0053] The central transparent area 4 employs an aspherical Fresnel lens (focal length f = 6mm) to compensate for the optical path offset caused by the curvature of the spherical mask, ensuring that the reflected light is precisely focused on the central region of the receiver. Through Zemax optimization, the spot diameter is <20μm within a central field of view of ±10°, meeting the requirements for high-resolution imaging.

[0054] The central transparent area is covered with a circularly polarized film, which is orthogonal to the linearly polarized light of the LED light source, suppressing specular reflection noise (such as attenuation of skin surface reflection >90%). Ultraviolet absorbers (such as benzotriazoles) are doped into the substrate of the transparent area to block interference from ambient ultraviolet light in the 300-400nm range.

[0055] During operation, the LED light source emits near-infrared pulsed light, which is diffused by a spherical mask and evenly covers the palm area (120mm in diameter). Veins absorb the infrared light, creating dark areas. Reflected light from the palm passes through the Fresnel lens at the center of the spherical mask and is focused onto the CMOS sensor, resulting in a high-contrast image of the vein pattern. The LED light source also emits visible light, which is evenly scattered onto the palm surface by the diffusion layer around the spherical mask, highlighting texture details. After registration using an algorithm, the combined palm print and vein features are extracted, achieving high-precision biometric recognition.

[0056] In some embodiments, each LED is front-mounted with a microlens to converge the original divergence angle to 60°, which, together with the spherical mask, achieves secondary optical diffusion.

[0057] In some embodiments, the receiver also includes a switchable filter (such as an 850nm bandpass filter and a visible light cutoff filter) that switches synchronously with the LED's time-division emission to improve the signal-to-noise ratio.

[0058] In some embodiments, the LED light source includes at least three sub-light sources evenly distributed around the receiver. At least three sub-light sources are arranged in a ring around the receiver at 120° equidistant angles to ensure basic symmetry. Preferably, 6-8 sub-light sources are distributed at 60° or 45° intervals to eliminate illumination dead zones and improve edge uniformity. The central axis of the sub-light sources coincides with the center of curvature of the spherical mask to avoid light path offset (e.g., a light source tilt angle of 15°-30° for outward divergence). Sub-light source wavelength selection:

[0059] Near-infrared sub-light source (850nm / 940nm): used for vein imaging, penetrating skin tissue to a depth of 3-5mm.

[0060] Visible light LED (450nm blue light / 520nm green light): Enhances the contrast of palm print surface texture.

[0061] Optional ultraviolet light source (395nm): excites specific fluorescent substances for in vivo detection.

[0062] Time-division pulse drive (e.g., 10kHz) alternates between near-infrared and visible light to avoid multispectral crosstalk.

[0063] Power is dynamically adjusted, and brightness is automatically adjusted based on the distance to the hand (feedback from a distance sensor) (range: 10-500mW / light source). A light-shielding grid (height ≥2mm) is installed around the sub-light source to block direct light from entering the receiver's field of view.

[0064] In some embodiments, the sub-light source is mounted with a 30° tilt angle facing outwards, and the central axis of the light source coincides with the center of curvature of the spherical mask. When the sub-light source is tilted outwards at 30°, the divergence angle of the light after refraction by the spherical mask can be extended to 120° (based on Snell's law: n1sinθ1=n2sinθ2, PMMA refractive index n=1.49, air n=1.0), achieving full coverage of the palm area (100-150mm in diameter). The 30° tilt ensures that the main light spot of the light source avoids the receiver's field of view (receiver field of view angle ±15°), reducing direct light interference (measured stray light intensity is reduced to less than 10% of that of traditional flat-mounted light sources).

[0065] The central axes of all sub-light sources converge at the center of curvature (geometric center) of the spherical mask, forming a radially symmetrical optical path. Light emitted from any sub-light source, after refraction by the spherical mask, has an equal optical path length on the target plane (palm) (error < 0.1 mm), eliminating edge brightness attenuation (illuminance uniformity > 95%). The sub-light sources are welded to an annular aluminum substrate with a 30° bevel. The inner diameter of the substrate matches the radius of curvature of the spherical mask (e.g., when R = 15 mm, the inner diameter of the substrate = 2R·sin30° = 15 mm). During installation, a laser alignment instrument is used to ensure that the extended optical axis of each sub-light source precisely intersects at the center of curvature of the spherical mask (positional deviation ≤ ±0.05 mm). The coefficients of thermal expansion of the aluminum substrate and the spherical mask (PMMA) are 23 × 10⁻⁶ / ℃ and 70 × 10⁻⁶ / ℃, respectively. Finite element analysis is used to optimize the gap design (leaving a 50 μm gap at 25℃) to avoid optical axis misalignment due to temperature rise.

[0066] In some embodiments, the LED light source emits at least two different types of light. The first is a near-infrared band (850-940nm), which has strong penetrating power into biological tissue and is used for subcutaneous vein imaging. The second is a visible light band (450-550nm), which has high reflectivity and captures details of palm prints on the epidermis. An optional third is an ultraviolet light band (365-395nm), which excites fluorescence in substances on the skin surface for in vivo detection. Time-division emission: Different LED bands are alternately illuminated (e.g., 10ms infrared light → 5ms interval → 10ms visible light) to avoid spectral overlap. Encoded modulation: The infrared light is modulated with a 1kHz square wave, while the visible light remains DC. The receiver separates the signals through frequency domain filtering.

[0067] In some embodiments, the spherical mask includes at least two different phosphors and emits light under at least two different light sources. The phosphor type needs to match the wavelength of the light.

[0068] First phosphor: Cerium-doped yttrium aluminum garnet (YAG:Ce) 3+ The excitation wavelength is 430-460nm (blue light), and the emission peak is 550-580nm (yellow-green light), which is used to enhance the visibility of palm print surface texture.

[0069] Second phosphor: Europium-doped nitride red phosphor (CaAlSiN3:Eu) 2+ The excitation wavelength is 360-410nm (ultraviolet to near ultraviolet), and the emission peak is 620-650nm (deep red light), which is used to penetrate the epidermis to display the subcutaneous microvascular structure.

[0070] Main excitation source: 450nm blue LED excites YAG phosphor to produce yellow-green light (550-580nm).

[0071] Auxiliary excitation light source: 395nm ultraviolet LED excites nitride red phosphor to produce deep red light (620-650nm).

[0072] Independent control: Dual-band LEDs operate in a time-sharing manner (e.g., blue light 10ms → ultraviolet light 10ms) to avoid spectral overlap.

[0073] Blue light excites yellow-green light (palmprint pattern)

[0074] A 450nm blue LED is lit up → YAG phosphor absorbs and downconverts → emits 550-580nm yellow-green light, which is diffused through the spherical mask microstructure to form a uniform surface light source.

[0075] Enhanced biometrics: The difference in reflectivity of yellow-green light in the stratum corneum of the palm is significant (the difference in reflectivity between dry and moist skin reaches 40%), improving the contrast of palm lines (MTF50 is increased to 25 lp / mm).

[0076] Ultraviolet-excited deep red light (vein mode)

[0077] 395nm ultraviolet LED is lit → Nitride red powder absorbs high-energy photons → emits 620-650nm deep red light, penetrating the epidermis to a depth of 2-3mm.

[0078] The principle of vein imaging: Deoxyhemoglobin in veins has a 3-5 times higher absorption rate of 620-650nm light than surrounding tissues, forming a dark outline with a spatial resolution of 0.5mm.

[0079] like Figure 2 As shown, different fluorescent powders form different patterns, such as circles, squares, and pentagons.

[0080] In some embodiments, the two different light rays are polarized light with a 90° phase difference, and the receiver is equipped with a corresponding polarization filter. The first light ray is linearly polarized light with a polarization direction of 0° (vertical direction), generated by adding a 0° linear polarizer in front of the LED light source. The second light ray is linearly polarized light with a polarization direction of 90° (horizontal direction), forming orthogonal polarization with the first light ray, and the phase difference is strictly controlled within 90°±5°. The two polarized lights are emitted alternately in a time-division manner (e.g., 10ms vertical polarization → 5ms gap → 10ms horizontal polarization) to avoid signal crosstalk.

[0081] Specular reflections from the skin surface retain their original polarization direction, and orthogonal polarization filters attenuate them by >95%, while diffuse reflections from subcutaneous tissue have randomized polarization and partially pass through the filters. Vertically polarized light penetrates the epidermis (0.5-1 mm), while horizontally polarized light is mainly scattered by the dermis (1-2 mm). The difference between the two channels reflects the depth distribution of blood vessels.

[0082] A linear polarizer (such as polyvinyl alcohol PVA) is laminated onto the surface of each LED chip, with a transmittance >80% and an extinction ratio >1000:1. The polarizer mounting angle is adjusted by a six-axis robotic arm with an error <±0.5° to ensure consistent polarization direction across multiple light sources. The LED driving timing is controlled by an FPGA, with strict time-sharing of vertical and horizontal polarized light, and a switching delay <1μs. The driving current is dynamically adjusted based on the transmittance differences of the polarizers (vertical / horizontal polarizers may have different efficiency due to manufacturing processes) (e.g., increasing the vertical photocurrent by 10%).

[0083] In some embodiments, the outer surface of the spherical cover is provided with a microprism array, and the inner surface is coated with an antireflective film. The prism unit is an isosceles triangular prism (vertex angle 90°, base angle 45°), with a unit size of 50μm×50μm, arranged in a hexagonal close-packed array to achieve omnidirectional diffusion. When the incident angle of light is between 0° and 60°, the exit angle is expanded to over 120° after two refractions (verified by LightTools simulation), eliminating the central light spot. Randomly perturbing the prism direction (±5°) disrupts periodic diffraction, resulting in an illuminance uniformity >98% (ANSI standard test).

[0084] Using nanoimprint lithography, a nickel template (Ra < 10 nm) is hot-pressed onto the PMMA surface, achieving a replication accuracy of ±0.1 μm and ensuring optical consistency. The surface is coated with a diamond-like carbon (DLC, 2 μm thick) film with a hardness > 8H. After passing the Taber abrasion resistance test (CS-10 wheel, 1 kg load, 1,000 cycles), the haze increase is < 2%.

[0085] The inner surface antireflective coating is a multilayer interference film: seven layers of alternating SiO2 (low refractive index n = 1.46) and TiO2 (high refractive index n = 2.35), with a total thickness of approximately 1.2 μm, optimized for dual-band illumination at 850 nm and 450 nm. Average reflectivity: <0.3% at 450 nm and <0.2% at 850 nm (measured data). Incident angle tolerance: reflectivity fluctuation <0.1% within the range of 0°-30°.

[0086] The coating process employs ion-assisted deposition (IAD): at 10 -4 Under vacuum conditions, the film density is improved by ion bombardment, and the adhesion reaches grade 5B (ASTM D3359) after humidity testing (85℃ / 85%RH, 500h). Edge masking: Masking technology is used to ensure that the transparent area (8mm in diameter) in the center of the spherical mask is free of coating, maintaining >99% light transmittance.

[0087] Light transmission path

[0088] Incident stage: LED light source light enters the inner surface of the spherical mask at an angle of ±30°. The anti-reflection film reduces the reflection loss from 4% to 0.3%, improving the light energy utilization rate.

[0089] Internal propagation: Light propagates through total internal reflection inside the PMMA, and the antireflective coating reduces interface scattering, achieving a transmission efficiency of 98.5% (compared to 92% for traditional planar masks).

[0090] Emission control: When light reaches the outer surface, the microprism array converts the collimated light into large-angle uniformly diffused light, with the divergence angle expanding from ±15° to ±60°, covering a palm area with a diameter of 150mm.

[0091] Polarization coordination: The microprism array combined with orthogonal polarization filters (such as 0° emission / 90° reception) makes the retroreflectivity of ambient stray light <0.01% (measured value).

[0092] 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.

[0093] 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 spherical brush palm mold module, characterized in that, The application relates to a LED light source, comprising: a LED light source for projecting light; a receiver located in the middle of the LED light source for receiving reflected signals of the light; a spherical mask located in the light path of the light for uniformly emitting the light; the center of the spherical mask is transparent so that the light can penetrate and irradiate on the receiver.

2. The spherical brush palm module of claim 1, wherein, The LED light source comprises at least three sub light sources uniformly distributed around the receiver.

3. The spherical brush palm module of claim 2, wherein, The sub light sources are installed at an outward 30-degree inclination angle, and the central axis of the light source coincides with the curvature center of the spherical mask.

4. The spherical brush palm module of claim 1, wherein, The LED light source emits at least two different kinds of light.

5. The spherical brush palm module of claim 4, wherein, The spherical mask comprises at least two different kinds of fluorescent powder and emits light under at least two different kinds of light.

6. The spherical brush palm module of claim 5, wherein, The different kinds of fluorescent powder form different patterns.

7. The spherical brush palm module of claim 4, wherein, The two different kinds of light are polarized light with a phase difference of 90 degrees, and the receiver is provided with a corresponding polarized filter.

8. The spherical brush palm module of claim 1, wherein, The LED light source comprises infrared light with a wavelength range of 850-940nm and visible light with a wavelength range of 450-550nm.

9. The spherical brush palm module of claim 1, wherein, The outer surface of the spherical mask is provided with a micro-prism array, and the inner surface is coated with an anti-reflection film.

10. The spherical brush palm module of claim 1, wherein, The transparent area of the spherical mask is provided with a Fresnel lens structure for focusing the reflected signals to the photosensitive surface of the receiver.

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