Live fingerprint identification system and fingerprint detection module

Abstract

This invention provides a live fingerprint recognition system and a fingerprint detection module. The fingerprint detection module includes a spectral chip, a circuit board, an optical component, and a bracket. The spectral chip is disposed on and electrically connected to the circuit board. The bracket is disposed on the circuit board, and the optical component is fixed by the bracket and supported by the bracket in the photosensitive path of the spectral chip. The reflected light from the fingerprint to be tested is received by the spectral chip through the optical component, and the spectral chip detects the fingerprint information based on the spectral information of the reflected light.

Description

Technical Field

[0001] This invention relates to the field of fingerprint detection, and more particularly to a live fingerprint recognition system and a fingerprint detection module. Background Technology

[0002] Various types of biometric systems are increasingly being used to provide enhanced security and / or improved user convenience. For example, fingerprint sensing systems, due to their small size, high performance, and widespread user acceptance, are widely used in various terminal devices, such as consumer smartphones. Currently, several fingerprint sensing systems are available on the market, such as those based on capacitive fingerprint modules and those based on optical fingerprint modules. While these types of fingerprint sensing systems can unlock devices, once applied to mobile terminals, they can be used to create fake fingerprints by stealing the user's fingerprint, thereby increasing the probability of fingerprint passwords being compromised and posing a significant threat to the information security of mobile terminals.

[0003] Existing fingerprint recognition devices mainly fall into two categories: optical fingerprint recognition and capacitive fingerprint recognition. Optical fingerprint recognition devices are generally larger, hindering device integration, while capacitive fingerprint recognition devices are expensive and easily constrained by chip production capacity. Furthermore, both types of fingerprint devices typically lack liveness detection capabilities, resulting in lower security. Existing liveness fingerprint recognition solutions all have certain drawbacks. For example, capacitive modules suffer from poor environmental stability, short lifespan, and insufficient liveness detection capabilities, while optical modules usually lack liveness detection functionality. Therefore, there is an urgent need for a simple and reliable fingerprint recognition solution to achieve liveness fingerprint recognition.

[0004] With the development of spectral technology, fingerprint recognition devices based on multispectral technology have gradually emerged. However, existing multispectral fingerprint liveness detection devices are large in size and have complex algorithms. The optical path primarily employs prisms and mirrors to deflect the light and improve image contrast, and the required types and numbers of illumination sources are numerous. The system often requires multiple frames of images to complete recognition and liveness detection. Furthermore, due to the low spectral accuracy, the liveness processing algorithm is complex, time-consuming, and has a high system load. While existing spectral detection devices are small in size, their internal structure is complex and they lack high-precision liveness recognition performance. Summary of the Invention

[0005] A key advantage of this invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the live fingerprint recognition system is suitable for live detection, thereby improving the applicability of the fingerprint detection device.

[0006] Another advantage of the present invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the live fingerprint recognition system makes a liveness determination based on the spectral information reflected by the skin, thereby realizing the liveness detection of fingerprints and improving the accuracy of detection.

[0007] Another advantage of the present invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the live fingerprint recognition system determines the recognition result of the object to be identified based on the comparison result of reference spectral response data and recognition spectral response data, which helps to improve the accuracy of fingerprint detection and recognition.

[0008] Another advantage of the present invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the live fingerprint recognition system includes a light source and a recognition module, wherein the light source is disposed at or adjacent to the recognition module and is used to illuminate the fingerprint to be tested.

[0009] Another advantage of the present invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the light source is disposed on the circuit board or frame of the recognition module, which is conducive to the miniaturization of the live fingerprint recognition system.

[0010] Another advantage of the present invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the live fingerprint recognition system obtains raw data, i.e. light intensity information, and performs image information correction and spectral information correction on the raw data respectively. Then, it uses fingerprint recognition algorithm and liveness algorithm respectively to compare the fingerprint image and spectral information with the corresponding information extracted during the recording to obtain the matching degree. When both matching degrees are higher than the threshold, the input verification is passed; otherwise, the output verification fails.

[0011] Another advantage of the present invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the live fingerprint detection method includes image information correction and spectral information correction, including an image processing method with surrounding mean compensation (binning), which improves the accuracy of data detection through weighted averaging.

[0012] Another advantage of the present invention is that it provides a live fingerprint recognition system and a fingerprint detection module, wherein the live fingerprint detection method further includes a liveness algorithm process, which extracts effective corrected spectral parameters (or spectral information) from the original data (light intensity information) after processing, forms a data group with the corresponding parameters of the entered data, and calculates the correlation coefficient R after linear fitting. When the correlation coefficient R is greater than the corresponding threshold, it is determined to be a live fingerprint; otherwise, it is determined to be a non-live fingerprint.

[0013] According to one aspect of the present invention, a fingerprint detection module is provided, comprising:

[0014] Spectroscopic chip;

[0015] Circuit board, wherein the spectral chip is disposed on the circuit board and electrically connected to the circuit board; and

[0016] An optical component, wherein the optical component is located in the photosensitive path of the spectral chip, so that the reflected light of the fingerprint to be tested is received by the spectral chip through the optical component, and the spectral chip detects fingerprint information based on the spectral information of the reflected light.

[0017] According to one embodiment of the present invention, the device further includes a light source assembly, wherein the light source assembly is disposed on the circuit board and electrically connected to the circuit board, and wherein the light generated by the light source assembly is emitted to the fingerprint to be tested.

[0018] According to one embodiment of the present invention, a bracket is further included, wherein the bracket is disposed on the circuit board, the optical component is fixed by the bracket, and the optical component is supported by the bracket in the photosensitive path of the spectral chip.

[0019] According to one embodiment of the present invention, a transparent cover plate is further included, wherein the transparent cover plate is disposed on the bracket, and wherein the transparent cover plate is located above the optical component.

[0020] According to one embodiment of the present invention, the bracket includes a first bracket and a second bracket, wherein the first bracket is located outside the second bracket, the transparent cover is fixed to the first bracket, the optical component is disposed on the second bracket, and the optical component is supported by the second bracket on the photosensitive path of the spectral chip.

[0021] According to one embodiment of the present invention, the light source assembly further includes at least one light source, the first bracket further has at least one cavity, wherein the light source of the light source assembly is located in the cavity of the first bracket, and the bracket is made of a transparent material.

[0022] According to one embodiment of the present invention, a heat dissipation element is further included, wherein the heat dissipation element is disposed on the circuit board, and the temperature of the fingerprint detection module is reduced by the heat dissipation element.

[0023] According to one embodiment of the present invention, the bracket includes a bracket body and an extension unit extending integrally inward from the bracket body, wherein the optical component is fixed to the photosensitive path of the spectral chip by the extension unit of the bracket.

[0024] According to one embodiment of the present invention, the bracket body further includes an upper bracket end and a lower bracket end integrally extending downward from the upper bracket end, wherein the lower bracket end is fixed to the circuit board, the light source assembly is located outside the lower bracket end, and wherein the bracket body of the bracket is made of transparent material.

[0025] According to one embodiment of the present invention, the light source assembly further includes at least one light source, and the support body further provides a clearance space, wherein the light source is located in the clearance space of the support body.

[0026] According to one embodiment of the present invention, the clearance space of the support body is formed at the lower end of the support body, wherein the clearance space is a space with one side opening downward; or the side of the clearance space is provided with an opening that can at least partially accommodate the light source.

[0027] According to one embodiment of the present invention, the bracket further includes a light-shielding unit, wherein the light-shielding unit is a light-shielding material with light-blocking properties, and wherein the light-shielding unit is formed at the lower end of the bracket body and the lower end of the extension unit.

[0028] According to one embodiment of the present invention, the bracket includes a bracket body and an extension unit integrally extending inward from the bracket body, wherein the optical component is fixed to the extension unit of the bracket, and the transparent cover is fixed to the upper end of the bracket body.

[0029] According to one embodiment of the present invention, the circuit board includes a first circuit board and a second circuit board, wherein the spectral chip is disposed on the first circuit board, the light source assembly is disposed on the second circuit board, and the second circuit board is fixed to the extension unit of the bracket.

[0030] According to one embodiment of the present invention, the light source assembly includes at least one light source and at least one light homogenizer located in the emission direction of the at least one light source, wherein the light homogenizer is located in the emission path of the light source and homogenizes the light emitted by the light source.

[0031] According to one embodiment of the present invention, the circuit board further includes a connection unit, wherein the connection unit connects the first circuit board and the second circuit board, and connects the light source of the light source assembly to the spectral chip disposed on the first circuit board through the connection unit.

[0032] According to one embodiment of the present invention, the light source assembly and the prism are further included, wherein the light source assembly is adjacent to the prism, wherein the light emitted by the light source assembly reaches the area to be tested through the prism, and the reflected light of the fingerprint to be tested is refracted by the prism to the optical assembly, and then received by the spectral chip through the optical assembly.

[0033] According to one embodiment of the present invention, the prism has an incident surface, a detection surface and at least one emitting surface, wherein the light source assembly is facing the incident surface of the prism, and the light emitted by the light source assembly enters the prism through the incident surface of the prism and reaches the detection surface.

[0034] According to one embodiment of the present invention, the light source assembly is disposed at the bottom of the prism, wherein the light source assembly further includes at least one light source and a light homogenizing layer, wherein the light homogenizing layer is disposed on the light incident surface of the prism, the light source and the light homogenizing layer are facing each other, and the light emitted by the light source is homogenized by the light homogenizing layer.

[0035] According to one embodiment of the present invention, the optical component of the fingerprint detection module is a microstructure array, the spectral chip includes a filter structure and an image sensor, wherein the microstructure array and the filter structure are located on the photosensitive path of the image sensor, and the microstructure array, the filter structure and the image sensor are stacked and integrated in sequence.

[0036] According to one embodiment of the present invention, the incident light emitted by the light source assembly has an energy of greater than or equal to 80% in the 400-600nm wavelength band.

[0037] According to one embodiment of the present invention, the energy of the incident light emitted by the light source assembly in the 400-500nm band does not exceed 80% of the energy in the 500-600nm band.

[0038] According to another aspect of the present invention, the present invention further provides a live fingerprint recognition system, comprising:

[0039] Main control unit;

[0040] An imaging unit, wherein the imaging unit includes an imaging device and a spectral chip, and the imaging device is located on the photosensitive path of the spectral chip;

[0041] An illumination unit, wherein the illumination unit is located around the imaging unit; and

[0042] An algorithm unit, wherein the algorithm unit, the imaging unit, and the illumination unit are connected to the main control unit, the main control unit controls the illumination unit to emit probe light to the object under test, the reflected light from the object under test is received by the spectral chip through the imaging device, and the light intensity information of the reflected light is obtained, and the algorithm unit identifies the fingerprint information of the object under test based on the light intensity information. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the principle of the live fingerprint recognition system according to the present invention.

[0044] Figure 2 This is a schematic diagram of the framework of the live fingerprint recognition system according to the present invention.

[0045] Figure 3 This is a schematic diagram of the white LED emission spectrum of the live fingerprint recognition system according to the present invention.

[0046] Figure 4 This is a schematic diagram of the system framework of the live fingerprint recognition system according to the present invention.

[0047] Figure 5 This is a schematic diagram of the identification method of the live fingerprint recognition system according to the present invention.

[0048] Figure 6 This is a schematic diagram of the spectral chip structure of a fingerprint detection module according to the present invention.

[0049] Figure 7 This is a schematic diagram of the fingerprint detection module according to the present invention.

[0050] Figure 8 This is a schematic diagram of the microstructure of a sensor in the fingerprint detection module according to the present invention.

[0051] Figure 9 This is a schematic diagram of the spectral pixel structure of the sensor in the fingerprint detection module according to the present invention.

[0052] Figure 10 This is a schematic diagram of the structure of the spectral chip of the sensor in the fingerprint detection module according to the present invention.

[0053] Figure 11 This is a schematic diagram of the microstructure of the spectral chip of the sensor in the fingerprint detection module according to the present invention.

[0054] Figure 12 This is a schematic diagram of the physical pixels of the spectral chip of the fingerprint detection module according to the present invention.

[0055] Figure 13This is a schematic diagram of the fingerprint detection module according to the present invention.

[0056] Figure 14 This is a schematic diagram of the structure of a fingerprint detection module according to a first preferred embodiment of the present invention.

[0057] Figure 15 This is a schematic diagram of another optional embodiment of the fingerprint detection module according to the first preferred embodiment of the present invention.

[0058] Figure 16 This is a schematic diagram of another optional embodiment of the fingerprint detection module according to the first preferred embodiment of the present invention.

[0059] Figure 17 This is a schematic diagram of the structure of a fingerprint detection module according to a second preferred embodiment of the present invention.

[0060] Figure 18 This is a schematic diagram of the structure of a fingerprint detection module according to a third preferred embodiment of the present invention.

[0061] Figure 19 This is a schematic diagram of another optional embodiment of the fingerprint detection module according to the preferred embodiment of the present invention.

[0062] Figure 20 This is a schematic diagram of the microlens array surface structure of the fingerprint detection module according to the preferred embodiment of the present invention.

[0063] Figure 21 This is a schematic diagram of the structure of a fingerprint detection module according to a fourth preferred embodiment of the present invention.

[0064] Figure 22 This is a schematic diagram of another optional embodiment of the fingerprint detection module according to the fourth preferred embodiment of the present invention.

[0065] Figure 23 This is a schematic diagram of a support structure for the fingerprint detection module according to the fifth preferred embodiment of the present invention.

[0066] Figure 24 This is a schematic diagram of another optional embodiment and structure of the fingerprint detection module according to the fifth preferred embodiment of the present invention.

[0067] Figure 25 This is a schematic diagram of another optional embodiment of the fingerprint detection module according to the fifth preferred real-time exchange rate of the present invention.

[0068] Figure 26 This is a schematic diagram of fingerprint region division according to any of the preferred embodiments of the present invention. Detailed Implementation

[0069] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments only relate to a portion of the implementations of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments disclosed in this application without creative effort are within the scope of protection of this application. The terms "comprising" and "having," and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, a process, method, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not specifically listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0070] Those skilled in the art should understand that in the description of this application and the claims, the orientation or positional relationship indicated by certain terms is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device, mechanism, structure or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as a limitation of this application.

[0071] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this term in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0072] Overview of live fingerprint recognition systems and fingerprint detection modules

[0073] The live fingerprint recognition system of this application belongs to optical fingerprint recognition and adopts a direct imaging method. The imaging unit of the live fingerprint recognition system directly images the finger placed on the transparent cover, which greatly reduces the size of the module. In addition, it can acquire the spectral information generated by the reflection of the object under test during imaging, and perform accurate liveness detection, which greatly improves the security level of the system. The live fingerprint recognition of this invention also covers the recognition of live palm prints.

[0074] like Figure 1As shown, due to the presence of physiological features such as capillaries (blood) and sweat pores in human skin, it is relatively more difficult to forge than fingerprint patterns. Furthermore, these physiological features cause the skin to absorb / reflect different wavelengths of the spectrum, indicating that liveness detection can be achieved by using the spectral information reflected from the skin. Specifically, reflection spectral tests on real fingers and fingerprint mold materials reveal a significant difference in the reflection spectra of real fingers and fingerprint mold materials within the 300nm-1100nm wavelength range. Figure 1 Taking tests on materials such as silicone, paper, and human skin as examples, the reflectance spectral data corresponding to real human fingers and fingerprint materials differ significantly. Therefore, it is feasible to determine liveness based on the received reflectance spectra.

[0075] like Figures 2 to 4 The present invention illustrates a live fingerprint recognition system, comprising a main control unit 100, an imaging unit 200, an illumination unit 300, and an algorithm unit 400. The main control unit 100 is electrically connected to the imaging unit 200, the illumination unit 300, and the algorithm unit 400, and controls the operation of these units. The illumination unit 300 emits incident light, which, upon striking the object to be measured (finger, palm, etc.), is reflected to form reflected light carrying detection information. This reflected light is received by the imaging unit 200, which acquires corresponding light intensity information. The algorithm unit 400 then processes this light intensity information to identify the texture and / or liveness information of the object to be measured.

[0076] Preferably, the incident light emitted by the illumination unit 300 is uniform light. Therefore, in this application, the illumination unit 300 includes a light source and a light homogenizer, which homogenizes the incident light projected by the light source. The light homogenizer can be a light homogenizer. The imaging unit 200 includes an imaging device and a spectral chip. The imaging device is located on the photosensitive path of the spectral chip. The imaging device may further include a lens group, a filter, etc. The algorithm unit 400 can provide a texture image restoration algorithm and / or a liveness detection algorithm in this invention. The illumination unit 300 is disposed around the imaging unit, and the light source and the spectral chip are electrically connected and fixed on the same circuit board; the light source and the spectral chip can also be disposed separately on different circuit boards, for example, the circuit board used to set the light source can be independently disposed on a bracket. Preferably, the light source is symmetrically distributed about the imaging unit, and can be distributed symmetrically along a circular ring, a square ring, or multiple points on the left and right, that is, the recognition system in this invention can have one or more light sources.

[0077] The light source is an LED, specifically a white LED or a monochromatic LED of a specific wavelength, such as an optical combination of red, green, blue, and NIR. It should be noted that in liveness detection, the main principle lies in the fact that physiological characteristics cause the skin to absorb / reflect different wavelengths of light. Experiments have shown that the skin is more sensitive to spectral absorption / reflection in the 400-600nm range, especially 500-600nm. Therefore, the light source of this invention preferably emits incident light with strong intensity in the 400-600nm range, while the intensity in other wavelength ranges is relatively weaker. More preferably, the 500-600nm range has the strongest light intensity. For example, the relative intensity distribution of the source spectrum should satisfy the following: the energy is mainly distributed between 500nm and 600nm, the distribution in this range is relatively flat, and there should be no significant peaks; there is a small amount of energy distribution between 400nm and 500nm, the energy integral of which is no higher than 80% of the 500nm-600nm range, and there should be no significant peaks; the light intensity in the spectral range outside 400nm-600nm is as weak as possible, and the total energy in this range is no higher than 20% of the total radiant energy of the light source.

[0078] like Figure 4 As shown, the identification system may further include a wake-up unit 500, wherein when the identification system is in standby mode, the wake-up unit 500 activates the identification system to enter normal working mode when a finger approaches or touches it. The wake-up unit 500 may employ an infrared beam mechanism or a touch wake-up mechanism, for example, by mounting a trigger capacitor on a circuit board, which will wake up the identification system when the object under test touches it.

[0079] like Figure 5 As shown, according to another aspect of the present invention, the fingerprint recognition method of the recognition system of the present invention is explained. The fingerprint texture and liveness detection process can be selected to be processed in parallel or serially according to system performance and actual needs, and the liveness detection function can be turned on and off separately. Specifically, the finger to be tested is placed in the testing area, and the illumination unit 300 emits an incident light to the finger to be tested. Part of the incident light is absorbed by the finger to be tested, and part is reflected to form a reflected light. The reflected light is collected by the imaging unit 200 to obtain the corresponding light intensity information. The light intensity information includes image information and spectral information. The image information is used for fingerprint image recognition, and the spectral information is used for spectral data analysis to determine liveness. Then, the fingerprint image is matched with a pre-stored reference fingerprint image. At the same time, the spectral information can be used in parallel or serially to determine liveness. If both pass, the verification is successful; otherwise, the system will issue an alarm.

[0080] Referring to the accompanying drawings of this invention Figures 6 to 13As shown, a fingerprint detection module according to another aspect of the present invention will be described below. The fingerprint detection module includes a spectral chip 10 and a circuit board 20. The spectral chip 10 is electrically connected to the circuit board 20 to receive reflected light and acquire light intensity information. Specifically, the spectral chip 10 includes a filter structure 11 and an image sensor 12. The filter structure 11 is located on the photosensitive path of the image sensor 12, and the filter structure 11 is a broadband filter structure in the frequency domain or wavelength domain. The pass spectra of different wavelengths of the filter structures 11 are not completely identical at different locations. The filter structure 11 can be a metasurface, photonic crystal, nanopillar, multilayer film, dye, quantum dot, MEMS (microelectromechanical systems), FP etalon, cavity layer, waveguide layer, diffraction element, or other structures or materials with filtering properties. For example, in the embodiments of this application, the filter structure 11 can be the light modulation layer in Chinese Patent CN201921223201.2. The image sensor 12 can be a CMOS image sensor (CIS), CCD, array photodetector, etc. Additionally, the spectral device includes a data processing unit, which can be a processing unit such as an MCU, CPU, GPU, FPGA, NPU, ASIC, etc., capable of exporting the data generated by the image sensor 12 for external processing.

[0081] The spectral chip 10 is used to acquire fingerprint path image information and finger spectral feature information to verify finger biometrics. The chip size ranges from 1 / 9' to 1 / 1.6', with an imaging spatial resolution of over 50,000 pixels, and has a spectral discrimination capability equivalent to a spectral resolution below 30nm. The spectral chip 10 can be attached to the circuit board 20 using COB, CSP, or FC packaging processes.

[0082] It is worth mentioning that in this invention, the spectral chip 10 denotes the intensity signal of the incident light at different wavelengths λ as f(λ), and the transmission spectrum curve of the filter structure as T(λ). The spectral chip 10 has m sets of filter structures, each with a different transmission spectrum, also called a "structural unit," which can be denoted as Ti(λ) (i=1,2,3,…,m). Each set of filter structures has a corresponding physical pixel below it, which detects the light intensity information Ii modulated by the filter structure. In this application, one physical pixel corresponding to one set of structural units is used as an example for illustration, but it is not limited to this. In other embodiments, multiple physical pixels can also form a set corresponding to one set of structural units.

[0083] The relationship between the spectral distribution of incident light and the measurements from the image sensor can be expressed by the following formula:

[0084] Ii = Σ(f(λ)·Ti(λ)·R(λ))

[0085] Where R(λ) is the response of the image sensor, denoted as:

[0086] Si(λ) = Ti(λ)•R(λ)

[0087] The above equation can then be extended into matrix form:

[0088]

[0089] Where Ii (i=1,2,3,…,m) is the response of the image sensor after the light to be measured passes through the broadband filter structure, corresponding to the light intensity information of m image sensors, also known as m "physical pixels", which is a vector of length m. S is the system's response to light of different wavelengths, determined by the transmittance of the filter structure and the quantum efficiency of the image sensor response. S is a matrix, where each row vector corresponds to the response of a structural unit to incident light of different wavelengths. Here, the incident light is sampled discretely and uniformly, with a total of n sampling points. The number of columns in S is the same as the number of sampling points of the incident light. Here, f(λ) is the light intensity of the incident light at different wavelengths λ, which is the incident light spectrum to be measured.

[0090] In practical applications, the system's response parameter S is known. By using the light intensity reading I from the image sensor, the spectrum f of the input light can be obtained through algorithmic deduction (which can be understood as spectral recovery). The process can employ different data processing methods depending on the specific circumstances, including but not limited to: least squares, pseudo-inverse, equalization, least-norm, artificial neural networks, etc.

[0091] The above example, using one physical pixel corresponding to a set of structural units, illustrates how to recover spectral information, also known as a "spectral pixel," using m sets of physical pixels (i.e., pixels on an image sensor) and their corresponding m sets of structural units (identical structures on the modulation layer are defined as structural units). It is worth noting that in this embodiment, multiple physical pixels can also correspond to a set of structural units. Further, a set of structural units and at least one corresponding physical pixel constitute a unit pixel; in principle, at least one unit pixel constitutes a spectral pixel.

[0092] Based on the above implementation method, arraying the spectral pixels can realize a snapshot-type spectral imaging device.

[0093] like Figure 8 As shown, 1896 is used. 1200 pixel image sensor ( Figure 8 (A portion of the image sensor area is shown), and m=4 is selected, i.e., 4 are selected. Four units of pixels form a spectral pixel, thus achieving 474. The image sensor comprises 300 independent spectral pixels, each of which can be individually calculated using the method described above. When combined with components such as a lens assembly, this image sensor can perform snapshot-style spectral imaging of the object under test, enabling the acquisition of spectral information for every point on the object in a single exposure.

[0094] Based on this, the selection method of spectral pixels can be rearranged according to actual needs, without making any adjustments to the image sensor, to improve spatial resolution. For example... Figure 9 As shown, you can select a close arrangement of solid and dashed boxes to increase the spatial resolution in the example above from 474. 300 increased to nearly 1896 1200.

[0095] Furthermore, the spatial and spectral resolutions of the same image sensor can be rearranged as needed. For example, in the above example, when a higher spectral resolution is required, an 8-bit resolution sensor can be used. Eight unit pixels form one spectral pixel; when higher spatial resolution is required, 3 can be used. Three physical pixels form one spectral pixel. That is, the spectral chip 10 acquires light intensity information, which can be used for both imaging and spectral reconstruction. For example, in a live fingerprint recognition system, the light intensity information can include image information and spectral information; the image information is used for fingerprint ridge image reconstruction, and the spectral information is used to determine liveness.

[0096] In this invention, the spectral chip 10 has a modulation region 101 and a non-modulation region 102. The modulation region 101 has a filter structure on the optical path of the image sensor 12, while the non-modulation region 102 does not have a filter structure. That is, the incident light is modulated by the filter structure in the modulation region before being received by the image sensor 12. The non-modulation region 102 is not modulated. For example, when the image sensor is a CMOS chip, the non-modulation region 102 is directly implemented as black and white pixels (i.e., no Bayer array is provided on the CMOS chip). Preferably, the modulation region 101 can acquire spectral information, and the non-modulation region 102 can acquire image information. In some embodiments, the non-modulation region 102 can also be implemented as a Bayer array, microlens array, convex lens, concave lens, Fresnel lens, etc., to adjust the incident light.

[0097] In this invention, the area of ​​the modulation region 101 accounts for 10%-50% of the effective area of ​​the spectral chip 10, preferably 12%-25%. Optionally, at least a portion of the modulation region 101 and the non-modulation region 102 are spaced apart. Therefore, during processing and analysis, the image information of the non-modulation region 102 surrounding the modulation region 101 can be combined with the spectral information of the modulation region 101 to optimize the spectral information, for example, to remove background noise, making the spectral information more accurate. Specifically, the average value of the image information of the surrounding non-modulation region 102 can be taken, and then the value of the modulation region 101 can be divided by or subtracted from the average value of the image information of the surrounding non-modulation region 102; or the spectral information can be used to assist in image restoration. In this way, the spectral information will have more information. At the same time, since the modulation region 101 is provided with structural units, its information is different from that of the non-modulation region 102. Therefore, there will be information gaps in this region during imaging. Therefore, the spectral information obtained from the modulation region 101 can be used to calculate and compensate for the image information in this region, or to correct the image information of its adjacent regions. For example, Figure 12 As shown, taking the filter structure 11 corresponding to one physical pixel as an example, there are two physical pixels between two adjacent filter structures; that is, one physical pixel with a structural unit is surrounded by eight physical pixels.

[0098] In this invention, since the modulation region 101 may lack image information for calculation, its image information value can also be calculated using the image information values ​​obtained from the physical pixels of the surrounding non-modulation regions 102. Specifically, the average value of the image information of the surrounding physical pixels can be used as the image information value of the modulation region 101, thereby making the entire image more complete. Taking the physical pixels corresponding to one structural unit surrounded by 8 physical pixels in the figure below as an example, the image information value of the middle modulation region can be calculated using the surrounding 8 physical pixels; alternatively, the average value of the surrounding 24 physical pixels can be used to calculate the image information value corresponding to the middle modulation region.

[0099] The circuit board 20 can be a flexible printed circuit board (FPC), a rigid printed circuit board (PCB), a rigid-flex PCB (F-PCB), a ceramic substrate, etc. The circuit board 20 is used for driving, controlling, processing, and outputting data for the light source and sensor chip.

[0100] The fingerprint detection module further includes an optical component 30, which is located on the optical path of the spectral chip 10. Preferably, in this application, the optical component 30 is a lens assembly, that is, the optical component 30 consists of at least one lens. More preferably, the lens assembly is used to image the finger to be tested in the test area onto the spectral chip 10, with a field of view (FOV) between 80 and 130 degrees, a back focal length between 0.3 mm and 5 mm, and a total optical length between 1 mm and 10 mm. The optical component 30 further includes a filter element to filter reflected light. For example, the filter element cuts off wavelengths above 650 nm or 600 nm, that is, only reflected light below 650 nm or 600 nm is allowed to pass through, preventing external ambient light from interfering with the test results. It is understood that the filter element can be adjusted or selected according to actual needs.

[0101] The fingerprint detection module further includes a bracket 40, which is disposed on the circuit board 20. The optical component 30 is disposed on the bracket 40 and is supported by the bracket 40 to maintain the optical path of the optical component 30 on the spectral chip 10.

[0102] The fingerprint detection module further includes a transparent cover plate 50, with the area to be tested formed on the surface of the transparent cover plate 50 for placing the finger or palm to be tested. The transparent cover plate 50 can be, but is not limited to, optical glass (glass cover plate) or optical plastic, with a thickness of 0.8mm-1.2mm. The fingerprint detection module further includes at least one light source assembly 60, which is used to illuminate the finger or palm to be tested. Preferably, the light emitted by the light source assembly 60 has a certain spectral width (≥30nm). Preferably, in this application, the light source assembly 60 can emit monochromatic light or mixed light as needed. Preferably, the light source assembly 60 includes a light source 61 and a light homogenizer 62, wherein the incident light emitted by the light source 61 is homogenized by the light homogenizer 62 before being projected onto the finger or palm to be tested.

[0103] The light-diffusing element 62 is located between the light source 61 and the transparent cover plate 50. The light-diffusing element 62 is made of transparent optical plastic, with a frosted surface and can be filled with a certain proportion of light-diffusing powder. It is worth mentioning that the upper and lower surfaces of the light-diffusing element 62 (the surface close to the light source and the surface close to the transparent cover plate) can be designed according to the light pattern of the light source to maximize light diffusion and improve the light uniformity on the outer surface of the module cover plate. Figure 13 As shown, a better uniform light effect can be obtained by adjusting the angle between the light source and the circuit board 20.

[0104] Example 1

[0105] like Figures 14 to 16 As shown, the fingerprint detection module according to a first preferred embodiment of the present invention will be described in the following description. The fingerprint detection module includes a spectral chip 10, a circuit board 20, an optical component 30, and a bracket 40. The spectral chip 10 is electrically connected to the circuit board 20. The optical component 30 is disposed on the bracket 40 and held in the photosensitive path of the spectral chip 10 by the bracket 40. The bracket 40 is fixed to the circuit board 20 and has a light-transmitting hole 401 located directly above the optical component 30, through which light to be detected is obtained.

[0106] The optical component 30 is implemented as a lens group, wherein the optical component 30 includes at least one optical lens. The optical lens of the optical component 30 is fixed above the spectral chip 10 by the bracket 40, and the light to be detected is processed by the optical component 30.

[0107] Accordingly, the bracket 40 includes a bracket body 41 and an extension unit 42 integrally extending inward from the bracket body 41. The upper end of the bracket body 41 forms the light-transmitting hole 401. The extension unit 42 extends inward from the bracket body 41 and forms a support structure with a light-transmitting hole 402 in the middle. The optical component 30 is disposed in the light-transmitting hole 402 formed by the extension unit 42, and the extension unit 42 supports the optical component 30 in the photosensitive path of the spectral chip 10.

[0108] The fingerprint detection module further includes a transparent cover plate 50, wherein the transparent cover plate 50 is disposed on the support body 41 of the bracket 40, and is fixed and supported by the support body 41. The transparent cover plate 50 may be, but is not limited to, a transparent glass or transparent plastic structure. The transparent cover plate 50 is placed over the photosensitive path of the spectral chip 10, and provides a structure suitable for fingerprint acquisition.

[0109] The fingerprint detection module further includes a light source assembly 60, which is electrically connected to the circuit board 20, and the light source assembly 60 provides a light source for the fingerprint detection module's recognition process.

[0110] Preferably, in this preferred embodiment of the invention, the light source assembly 60 is disposed on the extension unit 42 of the bracket 40, wherein the light-emitting surface of the light source assembly 60 faces the transparent cover plate 50.

[0111] The circuit board 20 includes a first circuit board 21 and a second circuit board 22, wherein the first circuit board 21 is electrically connected to the spectral chip 10, and the light source assembly 60 is electrically connected to the second circuit board 22; wherein the first circuit board 21 is disposed at the lower end of the bracket 40, and the second circuit board 22 is disposed at the extension unit 42 of the bracket 40. That is, the light source assembly 60 is fixed to the extension unit 42 of the bracket 40 via the second circuit board 22.

[0112] like Figure 14 As shown, the light source assembly 60 includes at least one light source 61 and at least one light homogenizer 62 located in the light emission direction of the at least one light source 61. The light homogenizer 62 is located on the light emission path of the light source 61 and homogenizes the light emitted by the light source 61. It is worth noting that in this preferred embodiment of the present invention, the light source assembly 60 is the illumination unit 300 in the live fingerprint recognition system.

[0113] like Figure 15 As shown, in this preferred embodiment of the present invention, the circuit board 20 further includes a connection unit 23, wherein the connection unit 23 connects the first circuit board 21 and the second circuit board 22, and the connection unit 23 connects the light source 61 of the light source assembly 60 to the spectral chip 10 disposed on the first circuit board 21.

[0114] The bracket 40 is further provided with at least one vent 403, wherein the vent 403 connects the inside and outside of the bracket 40, and conducts heat outward through the vent 403 to prevent heat accumulation inside the bracket 40. It is understood that the light source generates a large amount of heat during operation, and the corresponding bracket 40, optical component 30, and transparent cover plate 50 form a relatively sealed space, which can easily lead to overheating and affect the lifespan of the device. Therefore, in this preferred embodiment of the present invention, the vent 403 of the bracket 40 is formed at the upper end of the bracket 40.

[0115] Preferably, in this preferred embodiment of the present invention, the vent 403 is formed at the top of the transparent cover plate 50 and the support body 41 of the support 40. Specifically, when the transparent cover plate 50 is attached to the support 40 with adhesive such as glue, at least a portion of the area is left unattached during the glue application process. After the transparent cover plate 50 is placed on the support 40, the unattached area forms the vent, thereby dissipating heat.

[0116] Optionally, the vent 403 is formed on the support body 41 of the support 40, that is, the support 40 has an opening at the upper end, the transparent cover plate 50 is fixed on the support 40, and the opening at the upper end of the support 40 and the transparent cover plate 50 form the vent.

[0117] like Figure 15 As shown, the connection unit 23 of the circuit board 20 connects the first circuit board 21 and the second circuit board 22, wherein the connection unit 23 extends from the first circuit board 21 to the second circuit board 22. Preferably, the connection unit 23 is a metal wire, and the connection unit 23 passes through the extension unit 42 of the bracket 40.

[0118] Accordingly, the bracket 40 is further provided with at least one through hole 404, wherein the through hole 404 passes through the extension unit 42 of the bracket 40. One end of the connecting unit 23 is connected to the second circuit board 22 and passes through the through hole 404 of the bracket 40 to connect to the first circuit board 21. Accordingly, the first circuit board 21 is also provided with a corresponding fixing through hole, and the other end of the metal wire passes through the fixing through hole and is fixed to the first circuit board 21.

[0119] like Figure 16 As shown, optionally, in this preferred embodiment of the invention, the circuit board 20 further includes a connection unit 23A, wherein the connection unit 23A electrically connects the first circuit board 21 and the second circuit board 22. In this preferred embodiment of the invention, the connection unit 23A is implemented as a flexible printed circuit board (FPC). The connection unit 23A is disposed outside the bracket 40, with one end connected to the first circuit board 21 and the other end connected to the second circuit board 22. In other words, in this preferred embodiment of the invention, the circuit board 20 has a flexible printed circuit board structure, wherein the first circuit board 21 is fixed to the extension unit 42 of the bracket 40 after being folded.

[0120] Optionally, in another embodiment of the present invention, the connecting unit 23 is a circuit pattern formed on the surface of the bracket 40 based on laser-direct-structuring (LDS) technology, and the first circuit board 21 and the second circuit board 22 are connected through the circuit pattern. In this preferred embodiment of the present invention, the circuit pattern can also be directly implemented as the second circuit board 22, that is, the light source is directly connected to the circuit pattern.

[0121] Optionally, in another embodiment of the present invention, the connecting unit 23 is a conductive bracket formed on the bracket 40 by injection molding. The connecting unit 23 is a conductive circuit built into the bracket 40. After the bracket 40 is fixed to the first circuit board 21, one end of the conductive circuit is connected to the first circuit board 21 to achieve circuit conduction, and the other end is formed in the extension portion. When the second circuit board 22 is fixed to the extension portion, the second circuit board 22 is connected to the other end of the conductive circuit, thereby achieving conduction between the first circuit board 21 and the second circuit board 22. In another embodiment of the present invention, the other end of the conductive circuit is directly connected to the light source 61, and the conductive circuit can be regarded as the second circuit board 22.

[0122] Example 2

[0123] like Figure 17 As shown, the fingerprint detection module according to the second preferred embodiment of the present invention will be described in the following description. The fingerprint detection module includes a spectral chip 10, a circuit board 20, an optical component 30, a bracket 40A, a transparent cover plate 50, and a light source assembly 60, wherein the spectral chip 10 is electrically connected to the circuit board 20, the optical component 30 is disposed on the bracket 40A, and the optical component 30 is held in the light-sensitive path of the spectral chip 10 by the bracket 40.

[0124] Unlike the preferred embodiment described above, the structure of the bracket 40A is as follows: Specifically, the bracket 40A includes a first bracket 43A and a second bracket 44A, wherein the first bracket 43A is located outside the second bracket 44A, the transparent cover plate 50 is fixed to the first bracket 43A, the optical component 30 is disposed on the second bracket 44A, and the optical component 30 is supported on the photosensitive path of the spectral chip 10 through the second bracket 44A.

[0125] The second bracket 44A has a light-transmitting hole 440A, wherein the optical component 30 is fixed by the second bracket 44A to the light-transmitting hole 440A. It is understood that the light-transmitting hole 440A of the second bracket 44A faces the photosensitive surface of the spectral chip 10. The first bracket 43A is supported on the outside of the second bracket 44A, and the optical component 30 is fixedly supported by the second bracket 44A. The second bracket 44A, the optical component 30, and the circuit board 20 form a sealed environment. The spectral chip 10 is placed within the sealed space formed by the second bracket 44A, the optical component 30, and the circuit board 20.

[0126] The light source assembly 60 is disposed between the first bracket 43A and the second bracket 44A, and unlike the first preferred embodiment described above, the light source assembly 60 shares the same circuit board 20 with the spectral chip 10. The light source assembly 60 is disposed outside the second bracket 44A and electrically connected to the circuit board 20, while the first bracket 43A is located outside the light source assembly 60 and fixed to the circuit board 20. The light source assembly 60 includes a light source 61 and a light homogenizer 62. The light emitted by the light source 61 is homogenized by the light homogenizer 62 and then projected onto the test area of ​​the transparent cover plate 50.

[0127] Example 3

[0128] like Figure 18 As shown, the fingerprint detection module according to a third preferred embodiment of the present invention will be described in the following description. The fingerprint detection module includes a spectral chip 10, a circuit board 20, an optical component 30, and a bracket 40, wherein the spectral chip 10 is electrically connected to the circuit board 20, the optical component 30 is disposed on the bracket 40, and the optical component 30 is held in the photosensitive path of the spectral chip 10 by the bracket 40. The bracket 40 is fixed to the upper end of the circuit board 20, wherein the optical component 30 is fixed to the bracket 40.

[0129] The fingerprint detection module further includes a light source component 60B and a prism 70B, wherein the light source component 60B is adjacent to the prism 70B, wherein the light emitted by the light source component 60B reaches the area to be tested through the prism 70B, the reflected light from the fingerprint to be tested is refracted by the prism 70B to the optical component 30, and then received by the spectral chip 10 through the optical component 30.

[0130] In detail, the prism 70B has an incident surface 701B, a detection surface 702B, and at least one emitting surface 703B. The light source assembly 60B faces the incident surface 701B of the prism 70B directly. Light emitted from the light source assembly 60B enters the prism 70B through the incident surface 701B and reaches the detection surface 702B. The detection surface 702B of the prism 70B provides a detection area for detecting fingers or palms. The emitting surface 703B of the prism 70B corresponds to the optical assembly 30, wherein the reflected light to be detected is received by the spectral chip 10 through the optical assembly 30.

[0131] Preferably, the prism 70B has a hexahedral structure, wherein the light-incident surface 701B and the detection surface 702B of the prism 70B are surfaces formed at both ends of the prism 70B. As an example, in this preferred embodiment of the invention, the light-incident surface 701B is the bottom surface of the prism 70B, and the detection surface 702B is the top surface corresponding to the light-incident surface 702B. More preferably, the light-incident surface 701B and the detection surface 702B of the prism 70B are directly opposite each other, that is, the light-incident surface 701B and the detection surface 702B of the prism 70B are parallel surfaces.

[0132] The light-emitting surface 703B of the prism 70B is formed on the side surface of the prism 70B. Preferably, the side surface of the prism 70B extends outward and upward from the light-incident surface 701B to the detection surface 702B. It is worth mentioning that, in this preferred embodiment of the present invention, the number of light-emitting surfaces 703B of the prism 70B can be one or more.

[0133] The light source assembly 60B is disposed at the bottom of the prism 70B, wherein the light source assembly 60B further includes at least one light source 61B and a light homogenizing layer 62B, wherein the light homogenizing layer 62B is disposed on the light incident surface 701B of the prism 70B, the light source 61B and the light homogenizing layer 62B are facing each other, and the light emitted by the light source 61B is homogenized by the light homogenizing layer 62B.

[0134] It is understood that, in this preferred embodiment of the present invention, the homogenizing layer 62B is a homogenizing material or a frosted material coated on the bottom end of the prism 70B, so that the light emitted by the light source 61B is homogenized by the surface of the bottom surface. The homogenized incident light illuminates the finger or palm to be tested located in the test area in the prism, and then diffuse reflection occurs.

[0135] In this preferred embodiment of the present invention, the prism 70B has four sides, wherein the light-emitting surface 703B of the prism 70B is one side of the prism 70B. The light to be detected is emitted to the optical component 30 through the light-emitting surface 703B of the prism 70B. Therefore, it can be understood that in this preferred embodiment of the present invention, the light-emitting surface 703B of the prism 70B is located in the photosensitive path of the spectral chip 10.

[0136] Preferably, the remaining sides of the prism 70B are blackened, meaning that the light generated by diffuse reflection will be absorbed by the other three sides, which can reduce stray light from entering to a certain extent and also prevent light that affects measurement accuracy from being emitted from the first side.

[0137] Modified embodiments

[0138] like Figure 19 and Figure 20 As shown, another optional embodiment of the fingerprint detection module according to the preferred embodiment of the present invention will be described below. Since the recognition system needs to image the fingerprint texture, an optical component 30, such as an optical lens, is required. However, existing optical lenses are generally too large, especially in terms of the size along the optical path, resulting in an excessively tall module, which is not conducive to miniaturization.

[0139] Accordingly, in this preferred embodiment of the present invention, the optical component 30 of the fingerprint detection module is implemented as a microstructure array 110. Correspondingly, in this preferred embodiment of the present invention, the spectral chip includes a filter structure 120 and an image sensor 130, wherein the microstructure array 110 and the filter structure 120 are located on the light-sensing path of the image sensor 130. As an example, in this embodiment, the microstructure array is implemented as a pinhole array, a microlens array, or a superlens array, which can reduce the height of the module to a certain extent. Optionally, in another alternative embodiment, the pinhole array, microlens array, or superlens array can be integrated on the surface of the filter structure, that is, the microstructure array 110, the filter structure 120, and the image sensor 130 are sequentially stacked and integrated to form the fingerprint detection module.

[0140] It is worth mentioning that, in this invention, the fingerprint detection module includes a spectral chip 10 composed of a filter structure 120 and an image sensor 130, that is, the spectral chip 10 is composed of the filter structure 120 and the image sensor 130. Further, the spectral chip 10 further includes a modulation region 111 and a non-modulation region 112. Correspondingly, the microstructure array in this invention needs to be designed according to the structural characteristics of the actual spectral chip 10.

[0141] like Figure 20 As shown, taking a microlens array as an example, the microlens corresponding to the non-modulation region 112 have their focal points basically located on the surface of the image sensor, while the region corresponding to the modulation region 111 does not need to consider whether the microlens is focused. In some modified embodiments, the region corresponding to the modulation region 111 may not even have a microlens. That is to say, the microlens in the non-modulation region 112 has a one-to-one relationship with the pixels (physical pixels) on the image sensor, while the microlens in the modulation region 111 has a size that is basically consistent with the filter structure. For example, the structural unit of the filter structure in the modulation region 111 corresponds to n When there are n physical pixels, the corresponding microlens size is basically the same for n. The size of the array consists of n physical pixels, while the size of the microlens corresponding to the non-modulation region 112 is approximately equal to the size of the physical pixels. That is, the microstructure array is not regular; due to the specific characteristics of image sensor pixels, the local microstructure of the array varies.

[0142] Figure 20 The larger circle corresponds to the microstructure array of modulation region 111, and the smaller circle corresponds to the microstructure array of non-modulation region 112; the size of a single microlens corresponding to modulation region 111 is greater than or equal to the size of a single microlens corresponding to non-modulation region 112, ideally n n times, where n n is the number of physical pixels corresponding to the structural unit.

[0143] Example 4

[0144] Referring to the accompanying drawings of this invention Figures 21 to 22 As shown, a fingerprint detection module according to a fourth preferred embodiment of the present invention will be described in the following description. The fingerprint detection module includes a spectral chip 10, a circuit board 20, an optical component 30, and a bracket 40C, wherein the spectral chip 10 is electrically connected to the circuit board 20, the optical component 30 is disposed on the bracket 40C, and the optical component 30 is held by the bracket 40C in the light-sensing path of the spectral chip 10.

[0145] The bracket 40C further includes a first bracket 43C and a second bracket 44C, wherein the first bracket 43C is located outside the second bracket 44C, and the optical component 30 is disposed on the second bracket 44C and held in the photosensitive path of the spectral chip 10 by the second bracket 44C. The optical component 30, the second bracket 44C, and the circuit board 20 form a sealed space, wherein the spectral chip 10 is located within the sealed space.

[0146] The fingerprint detection module further includes a light source assembly 60C, wherein the light source assembly 60C is disposed on the circuit board 20 and electrically connected to the circuit board 20. The light source assembly 60C further includes at least one light source 61C, wherein the light source 61C may be, but is not limited to, an LED light source, and the light source 61C is arranged around the spectral chip 10. As an example, six LED light sources are symmetrically arranged on the outer side of the spectral chip 10.

[0147] The first bracket 43C is fixed to the circuit board 20, and the light source 61C is at least partially enclosed within the first bracket 43C. Preferably, the first bracket 43C further has at least one cavity 430C, wherein the light source 61C of the light source assembly 60C is located in the cavity 430C of the first bracket 43C.

[0148] Preferably, in this preferred embodiment of the present invention, the first support 43C is made of a transparent material, such as PC or PE, formed by injection molding, and then the first support 43C is frosted to give it a uniform light effect. The light emitted by the light source assembly 60 is directed outward through the first support 43C.

[0149] The first bracket 43C includes a first bracket body 431C and a mating member 432C extending integrally inward from the first bracket body 431C. The mating member 432C extends inward from the middle position of the first bracket body 431C to form a structure suitable for snapping onto the second bracket 44C, so that when the first bracket 43C is installed, it can be mated with the second bracket 44C (closely attached) to the outside of the second bracket 44C through the mating member 432C.

[0150] The fingerprint detection module further includes a transparent cover plate 50, wherein the transparent cover plate 50 is disposed at the end of the first bracket 43C and is fixed and supported by the first bracket 43C.

[0151] After the light source emits light, it is homogenized by the first bracket 43C and then projected onto the test area of ​​the transparent cover plate 50. The finger or palm to be tested is placed in the test area and reflects part of the homogenized light. The reflected light enters the spectral chip 10 after passing through the optical component 30, thereby obtaining the corresponding light intensity information. The light intensity information is used to determine the authenticity of the fingerprint and whether the person is alive.

[0152] It is understood that in this embodiment, the first support 43C not only supports the transparent cover plate 50 but also provides a uniform light effect. Furthermore, during the manufacturing process of the first support 43C, scattering particles are added to the original light-transmitting material to enhance the uniform light effect; these scattering particles can be substances such as titanium powder. Furthermore, the first support 43C is frosted to further improve its uniform light effect.

[0153] The bracket 40C further includes a light-shielding layer (not shown in the figure), wherein the light-shielding layer is coated on the outside of the first bracket 43C, and the light-shielding layer blocks the influence of external light on stray light.

[0154] like Figure 23As shown, the present invention further provides another optional embodiment of the fingerprint detection module according to the fourth preferred embodiment. The fingerprint detection module further includes a heat dissipation element 80C, wherein the heat dissipation element 80C is disposed on the circuit board 20, and the temperature of the fingerprint detection module is reduced by the heat dissipation element 80C.

[0155] Preferably, the circuit board 20 further includes at least one heat dissipation vent 202, wherein the heat dissipation vent 202 corresponds to the light source 61C, and the heat dissipation element 80C is disposed at the heat dissipation vent 202 of the circuit board 20. It is understood that the heat generated by the light source 61C can be dissipated through the heat dissipation element 80C located at the heat dissipation vent 202. It is understood that the heat dissipation element 80C may be, but is not limited to, filled with a heat-dissipating material, and the heat generated by the light source can be quickly dissipated through the heat dissipation element.

[0156] Example 5

[0157] Referring to the accompanying drawings of this invention Figures 23 to 25 As shown, a fingerprint detection module according to a fourth preferred embodiment of the present invention will be described below. The fingerprint detection module includes a circuit board 20, a bracket 40, a spectral chip 10, an optical component 30, a light source component 60, and a transparent cover plate 50. The spectral chip 10 is electrically connected to the circuit board 20, the bracket 40 is fixed to the circuit board 20, the optical component 30 is disposed on the bracket 40 along the photosensitive path of the spectral chip 10, and the transparent cover plate 50 is fixed to the bracket 40. The light source component 60 is disposed on the circuit board 20 and electrically connected to the circuit board 20.

[0158] The light source assembly 60 further includes at least one light source 61, wherein the light source 61 is located outside the bracket 40, and the light emitted by the light source 61 is incident on the transparent cover plate 50 through the bracket 40. Therefore, in this preferred embodiment of the present invention, the light source 61 is preferably obliquely disposed on the circuit board 20 or the light source 61 is disposed with a specific oblique illumination angle, wherein the light generated by the light source 61 is incident on the transparent cover plate 50 through the bracket 40.

[0159] Preferably, in this preferred embodiment of the present invention, the support 40 is made of a transparent material and has a light-uniforming effect. The light emitted by the light source 61 is uniformly diffused by the support 40 before being projected toward the transparent cover plate 50.

[0160] More preferably, in order to better illuminate the transparent cover plate 50, the light source 61 is set at a certain angle α with the circuit board 20, wherein 5° < α < 35°.

[0161] It is understood that in this preferred embodiment of the present invention, unlike the first preferred embodiment described above, the light source assembly 60 and the spectral chip 10 share the circuit board 20, but each of the light sources 61 of the light source assembly 60 is located outside the bracket 40.

[0162] The bracket 40 includes a bracket body 41 and an extension unit 42 integrally extending inward from the bracket body 41. The optical component 30 is fixed to the photosensitive path of the spectral chip 10 by the extension unit 42 of the bracket 40. The bracket body 41 of the bracket 40 is disposed on the circuit board 20, wherein the transparent cover plate 50 is disposed at the upper end of the bracket body 41. The bracket body 41 further includes an upper bracket end portion 411 and a lower bracket end portion 412 integrally extending downward from the upper bracket end portion 411, wherein the lower bracket end portion 412 is fixed on the circuit board 20, and the light source component 60 is located outside the lower bracket end portion 412.

[0163] The bracket 40 further includes a light-shielding unit 45, wherein the light-shielding unit 45 is a light-shielding material with light-blocking properties, and wherein the light-shielding unit 45 is formed at the lower end 412 of the bracket body 41 and the lower end of the extension unit 42. It is understood that light emitted by the light source can enter the spectral chip 10 through the lower end of the body, affecting the imaging accuracy of the spectral chip 10. Therefore, the present invention requires applying a layer of light-shielding unit 45 to the inner surface of the lower end of the body, and the lower and inner surfaces of the extension portion to prevent light emitted by the light source from directly entering the spectral chip 10.

[0164] like Figure 24 and Figure 25 As shown, another preferred embodiment of the fingerprint detection module of the present invention is further illustrated. Unlike the fifth preferred embodiment described above, at least a portion of the light source 61 is covered by the bracket 40. The bracket body 41 of the bracket 40 further provides a clearance space 410, wherein the light source 61 is located in the clearance space 410 of the bracket body 41. This allows the light emitted by the light source 61 to be homogenized by the bracket 40 as much as possible. On the one hand, this improves the homogenization effect of the light and the efficiency of projection onto the transparent cover plate 50; on the other hand, since the light source 61 is housed in the clearance space 410, its horizontal dimension is reduced to some extent.

[0165] The clearance space 410 of the bracket body 41 is formed at the lower end of the bracket body 41, wherein the clearance space 410 is a space with one side opening facing downward; or the side of the clearance space 410 is provided with an opening that can at least partially accommodate the light source 61.

[0166] In another optional embodiment of the present invention, the bracket 40 further includes an outer bracket (not shown in the figure), wherein the outer bracket is disposed on the outside of the bracket body 41. The outer bracket of the bracket 40 encloses the light source 61, the circuit board 20, etc., on the inner side of the outer bracket, thereby protecting the light source and the circuit board from exposure to the external environment.

[0167] like Figure 26 As shown, according to another aspect of this application, this application further provides an identification method for the aforementioned live fingerprint recognition system, wherein the liveness detection method is as follows:

[0168] Three wavelengths were selected in the violet band, five in the green band, eight in the red band, and eight in the near-infrared band, for a total of 24 bands. As shown in the figure below, the solid-lined box represents the effective imaging area of ​​the sensor, the dashed ellipse represents the fingerprint imaging area, and the dashed box represents the specific area from which spectral data is extracted.

[0169] When the system detects a fingerprint image, it calculates the center of the fingerprint region. A fixed area A is selected near the center. Pixel A, for example, box 1 in the image. Select four areas around box 1, and fix their size B. Pixel B, as shown in boxes 2-5 in the figure. The spectral values ​​of 24 bands in 5 regions, and the weights of the five regions, form a 1 A spectral feature vector of 125. The vector size varies with the number of regions; the required vector dimension is selected based on platform performance and security level.

[0170] The final vector can be represented as: S={(Rλ1,…, Rλn, r1)A1,(…)A2,…,( Rλ1,…, Rλn,rN )AN}, where R represents spectral reflectance, λn represents a selected wavelength, AN represents a selected region, and rN represents the weight of that region.

[0171] After the optical system is set up, samples need to be collected to confirm the algorithm parameters. When collecting spectral samples from real human fingers, attention should be paid to the hierarchical distribution; spectral samples from fingers of different genders, age groups, and occupations need to be collected. Samples of finger molds made of various materials should also be collected. Positive and negative samples are used to train an SVM to obtain an SVM parameter model. In use, the device extracts the spectral features of the object under test and synthesizes a feature vector, which is then input into the SVM to complete the liveness detection.

[0172] It is worth mentioning that in this embodiment, the spectral information does not necessarily need to be recovered to perform liveness detection. Instead, liveness detection can be performed directly based on the spectral response. Specifically, the reference spectral response data of the image sensor of the spectral analysis device to the reference object is obtained; the recognition spectral response data of the image sensor of the spectral analysis device to the object to be identified is obtained; and the recognition result of the object to be identified is determined based on the comparison result between the reference spectral response data and the recognition spectral response data.

[0173] This invention further provides a live fingerprint detection method based on the above-mentioned live fingerprint recognition device, wherein the spectral chip 10 obtains raw data, namely light intensity information, which includes image information and spectral information. The raw data is then corrected for both image information and spectral information. Then, the fingerprint recognition algorithm and the liveness algorithm are used respectively to compare the fingerprint image and spectral information with the corresponding reference information extracted during the recording process to obtain the matching degree. When both matching degrees are higher than the threshold, the input verification is passed; otherwise, the verification fails.

[0174] Image information correction and spectral information correction include image processing methods such as binning. Therefore, in this preferred embodiment of the invention, the live fingerprint detection method further includes steps of image information correction and spectral information correction. In image information correction, the intensity value of the spectral pixel (which can be understood as a filter structure corresponding to a physical pixel) is replaced with the intensity value of a weighted average of the intensities of nearby ordinary physical pixels, thereby generating corrected image information (image data). The average value can be selected from several neighboring ordinary physical pixels (e.g., 4, 8, 24, 80). When the number is greater than 4, the weighting kernel used for the weighted average can be a uniform kernel (equal weighting for all physical pixels) or a Gaussian kernel. For example... Figure 12 The illustrated embodiment can be implemented in 5 A Gaussian kernel of 5 is used, as shown in Table 1. The 0 in the middle represents a spectral pixel. That is, the light intensity information (image information) at this location needs to be obtained by Gaussian kernel weighted average of the light intensity information (image information) of the surrounding 24 physical pixels. That is, the light intensity information value of the relevant material pixel is multiplied by the sum of the corresponding coefficients and then divided by the sum of the weights.

[0175] Table 1

[0176]

[0177] For acquiring spectral information, it is necessary to avoid the influence of brightness in different locations on spectral verification. For example, the reflectivity of fingerprint valleys and ridges differs, resulting in different levels of brightness, which may affect the judgment of the spectral signal of the object under test. Therefore, the live fingerprint detection method of this preferred embodiment further includes a step of correcting the intensity of spectral pixels. For example, the intensity value of the current spectral pixel can be divided by or subtracted from the weighted average (binning) value of neighboring ordinary pixels to obtain the relative intensity, which is used as corrected spectral information for subsequent processing. Furthermore, the corrected spectral information can be filtered according to specific rules to remove excessively large or small values, thereby improving the effectiveness of the corrected spectral information. Figure 12 For example, you can take the average intensity value of the 8 physical pixels surrounding the spectral pixel, and then divide or subtract the average intensity value of the 8 physical pixels from the intensity value of the spectral pixel to obtain the corrected spectral information.

[0178] The live fingerprint detection method of the present invention further includes a liveness detection algorithm step. Effective corrected spectral parameters (which can also be understood as corrected spectral information) are extracted from the raw data (light intensity information) after processing, and the correlation coefficient R between the parameters and the reference spectral information is calculated (for example, the Pearson correlation coefficient can be used). When the correlation coefficient R is greater than the corresponding threshold, the person is determined to be alive; otherwise, they are determined to be inactive. Since the correlation coefficient R needs to be calculated in this invention, both the entered information and the detection information are vectorized into a one-dimensional vector.

[0179] The live fingerprint detection method of the present invention further includes the steps of threshold selection and application. For different data entries, due to potential changes in various conditions during entry, the noise power ratio (signal-to-noise ratio) varies with each data acquisition. Entry with a high signal-to-noise ratio generally results in a higher correlation coefficient between the corresponding spectral information and other entered reference spectral information; conversely, entry with a low signal-to-noise ratio generally results in a lower correlation coefficient. Therefore, using a uniform threshold for judgment can easily introduce misjudgments. To address this, this application eliminates the need for dynamic selection of a threshold and its corresponding application method, enabling more accurate liveness verification.

[0180] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with, but not limited to, technical features disclosed in this application that have similar functions.

Claims

1. A fingerprint detection module, characterized in that, include: Spectroscopic chip; A circuit board, wherein the spectral chip is disposed on the circuit board and electrically connected to the circuit board; as well as An optical component, wherein the optical component is located in the photosensitive path of the spectral chip, so that the reflected light of the fingerprint to be tested is received by the spectral chip through the optical component, and the spectral chip detects fingerprint information based on the spectral information of the reflected light; A bracket, wherein the bracket is disposed on the circuit board, the bracket includes a bracket body and an extension unit extending integrally inward from the bracket body, and the optical component is fixed to the photosensitive path of the spectral chip by the extension unit of the bracket. as well as A transparent cover plate, wherein the transparent cover plate is disposed on the bracket, and wherein the transparent cover plate is positioned above the optical component. The fingerprint detection module further includes a light source assembly, which is disposed on and electrically connected to the circuit board. The light generated by the light source assembly is emitted onto the fingerprint to be detected. The light source assembly includes at least one light source, the support is made of a transparent material, and the main body of the support is frosted and includes scattering particles. The main body of the support forms a clearance space, and the at least one light source is disposed in the clearance space. The clearance space of the bracket body is formed at the lower end of the bracket body, wherein the clearance space is a space with one side opening downward; or the side of the clearance space has an opening that at least partially accommodates the light source.

2. The fingerprint detection module according to claim 1, wherein, Alternatively, the support includes a first support and a second support, wherein the first support is located outside the second support, the transparent cover is fixed to the first support, the optical component is disposed on the second support, and the optical component is supported by the second support in the photosensitive path of the spectral chip. The first bracket further comprises at least one cavity, wherein the light source of the light source assembly is located in the cavity of the first bracket, the first bracket is made of a transparent material, the first bracket is frosted and includes scattering particles.

3. The fingerprint detection module according to claim 2 further includes a heat dissipation element, wherein the heat dissipation element is disposed on the circuit board, and the temperature of the fingerprint detection module is reduced by the heat dissipation element.

4. The fingerprint detection module according to claim 1, wherein the bracket further includes a light-shielding unit, wherein the light-shielding unit is a light-shielding material with light-shielding properties, and wherein the light-shielding unit is formed at the lower end of the bracket body and the lower end of the extension unit.

5. The fingerprint detection module according to claim 1, wherein the circuit board includes a first circuit board and a second circuit board, wherein the spectral chip is disposed on the first circuit board, the light source assembly is disposed on the second circuit board, and the second circuit board is fixed to the extension unit of the bracket.

6. The fingerprint detection module according to claim 5, wherein the light source assembly includes at least one light source and at least one light homogenizer located in the emission direction of the at least one light source, wherein the light homogenizer is located in the light emission path of the light source, and the light homogenizer homogenizes the light emitted by the light source.

7. The fingerprint detection module according to claim 6, wherein the circuit board further includes a connection unit, wherein the connection unit connects the first circuit board and the second circuit board, and connects the light source of the light source assembly to the spectral chip disposed on the first circuit board through the connection unit.

8. The fingerprint detection module according to claim 1 further includes a light source assembly and a prism, wherein the light source assembly is adjacent to the prism, wherein the light emitted by the light source assembly reaches the area to be tested through the prism, and the reflected light from the fingerprint to be tested is refracted by the prism to the optical assembly, and then received by the spectral chip through the optical assembly.

9. The fingerprint detection module according to claim 8, wherein the prism has a light-incident surface, a detection surface and at least one light-emitting surface, wherein the light source assembly is facing the light-incident surface of the prism, and the light emitted by the light source assembly enters the prism through the light-incident surface of the prism and reaches the detection surface.

10. The fingerprint detection module according to claim 9, wherein the light source assembly is disposed at the bottom of the prism, wherein the light source assembly further includes at least one light source and a light-diffusing layer, wherein the light-diffusing layer is disposed on the light-incident surface of the prism, the light source and the light-diffusing layer are facing each other, and wherein the light emitted by the light source is homogenized by the light-diffusing layer.

11. The fingerprint detection module according to claim 1, wherein the optical component of the fingerprint detection module is a microstructure array, the spectral chip includes a filter structure and an image sensor, wherein the microstructure array and the filter structure are located on the photosensitive path of the image sensor, and the microstructure array, the filter structure and the image sensor are stacked and integrated in sequence.

12. The fingerprint detection module according to any one of claims 1-3, 8 or 10, wherein the incident light emitted by the light source component has an energy of greater than or equal to 80% in the 400-600nm wavelength band.

13. The fingerprint detection module according to claim 12, wherein, The energy of the incident light emitted by the light source component in the 400-500nm wavelength band does not exceed 80% of the energy in the 500-600nm wavelength band.

14. A live fingerprint recognition system, characterized in that, include: Main control unit; An imaging unit, wherein the imaging unit includes an imaging device and a spectral chip, and the imaging device is located on the photosensitive path of the spectral chip; An illumination unit, wherein the illumination unit is located around the imaging unit; as well as The algorithm unit, including the imaging unit and the illumination unit, is connected to the main control unit. The main control unit controls the illumination unit to emit probe light to the object under test. The reflected light from the object under test is received by the spectral chip through the imaging device, and the light intensity information of the reflected light is obtained. The algorithm unit identifies the fingerprint information of the object under test based on the light intensity information. The imaging unit further includes a support, which comprises a support body and an extension unit extending integrally inward from the support body. The imaging device is fixed to the photosensitive path of the spectral chip by the extension unit. The support is made of a transparent material, and the support body is frosted and includes scattering particles. The lighting unit includes a light source assembly, which includes at least one light source. The support body forms a clearance space, and the at least one light source is disposed in the clearance space. The clearance space of the bracket body is formed at the lower end of the bracket body, wherein the clearance space is a space with one side opening downward; or the side of the clearance space has an opening that at least partially accommodates the light source.

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