WO2023063853A1

WO2023063853A1 - Device for identifying the veins of a user's palm

Info

Publication number: WO2023063853A1
Application number: PCT/RU2022/050324
Authority: WO
Inventors: Александр Владимирович ДРЕМИН
Original assignee: Общество с ограниченной ответственностью "Прософт-Биометрикс"
Priority date: 2021-10-14
Filing date: 2022-10-12
Publication date: 2023-04-20

Abstract

The invention relates to devices for obtaining an image of the veins of a user's palms and can be used in biometric identification systems for access monitoring and control. The essence of the invention consists in a device for identifying the veins of a user's palm comprising an emitter and an emitter polarizer arranged in series, as well as a radiation receiver, also arranged in series, with a receiver polarizer, the light wave intensity vector of which is perpendicular to the light wave intensity vector of the emitter polarizer, wherein the emitter polarizer has a multi-layer structure, one of the layers of which is in the form of a film containing a polarization grating, and another of the layers of which is made of a hard light-transmitting material. The technical result toward which the invention is directed is an increase in the degree of scattering of the light coming from the emitter.

Description

DEVICE FOR IDENTIFICATION OF THE USER'S PALM VEINS

The invention relates to devices for obtaining images of the user's palm veins and can be used in biometric identification systems for access control and management, authentication systems in financial, passport and visa systems and security systems in any industry.

Devices for identifying users using their biometric data are currently being actively developed, in particular devices that use the pattern of the user's palm veins as input. The operation of these devices is based on the principle of absorption of radiation in the infrared (IR) region of the spectrum by reduced hemoglobin in the vessels of the veins, as a result of which, when the user's palm is illuminated, only veins and blood vessels containing reduced hemoglobin become visible. To implement this principle, biometric user identification devices use IR spectrum radiation sources and receiving devices that read the user's vein pattern in the form of an image.

One of the examples of radiation sources is a radiation projection device known from the field of optics and polarization systems, containing a series-arranged emitter and an emitter polarizer having a multilayer structure, one of the layers being made in the form of a film containing a polarization grating deposited on a solid base, and more one of the layers is located above the polarizing grating and is made of a solid light-transmitting material, the surface of which is glossy [JP2009198638A, publication date: 03.09.2009, IPC: G02B 27/28, G02B 5/30, G02F 1/1335].

The disadvantage of the known technical solution is the insufficient degree of radiation scattering, due to the fact that the surface of the layer of solid light-transmitting material is made glossy, which does not allow for a sufficient degree of light scattering to uniformly illuminate the palm, as a result of which this technical solution cannot be used as part of palm vein identification devices. user.

As a prototype, a device for identifying the veins of the user's palm was chosen, containing a series-located emitter and a polarizer of the emitter, as well as a series-located radiation receiver with a polarizer of the receiver, the light wave intensity vector of which is perpendicular to the intensity vector of the light wave of the emitter polarizer, while the design of the polarizer is not disclosed in this security document [JP2011100317A, publication date: 05/19/2011, IPC: A61B 5/117, G06T 1/00, G06T 7/00] .

The advantage of the prototype over the known technical solution is the possibility of obtaining a device with a more contrast image of the veins of the palm, due to the implementation of the polarizer of the receiver and the polarizer of the emitter in such a way that their light wave intensity vectors are perpendicular to each other.

However, the disadvantage of the prototype is the increased risk of damage and failure of the polarizers of the receiver and emitter due to the fact that it is not possible to unequivocally state that the polarizer has a structure that protects it from external influences.

Known technical solutions, to one degree or another, can ensure the implementation of the principle of absorption of radiation in the IR region of the spectrum by reduced hemoglobin in the vessels of the veins, which is used by devices for identifying the veins of the user's palms, however, even in the case of the combined use of the above technical solutions, it remains necessary to create a technical solution devoid of inherent disadvantages, namely, the device for identifying the user's palm veins, which makes it possible to uniformly illuminate the user's palm and obtain a contrast image of the palm veins, which has a large area, which significantly increases the efficiency of biometric user identification, and at the same time, the device has such design features that reduce the risk of damage and failure of the polarizers of the device and significantly improve its performance.

The technical problem to be solved by the invention is the need to improve the efficiency of the user's biometric identification.

The technical result to which the invention is directed is to increase the degree of scattering of radiation coming from the emitter.

The essence of the invention is as follows.

The device for identifying the veins of the user's palm contains a emitter and a polarizer of the emitter located in series, as well as a sequentially located radiation receiver with a polarizer of the receiver, the light wave intensity vector of which is perpendicular to intensity vector of the light wave of the emitter polarizer, wherein the emitter polarizer has a multilayer structure, one of the layers is made in the form of a film containing a polarization grating, and another of the layers is made of a solid light-transmitting material. Unlike the prototype, one surface of the layer of solid light-transmitting material of the emitter polarizer is made light-scattering.

The user's palm vein identification device comprises a housing that accommodates elements of the palm vein identification device. The housing may be made of any structural material that is opaque. The body can be made in the form of a parallelepiped, a cylinder or a polyhedron having a cavity for placing the device elements.

The housing contains a flat cover made of a translucent material and acting as an infrared filter that transmits light only in a given region of the spectrum. The lid in longitudinal section may have a shape corresponding to the shape of the hollow part of the housing, in particular the lid may have the shape of a square, circle or polygon. The cover can be attached to the housing using any elements of a detachable or permanent connection. The lid can be provided with an antireflection coating, which makes it possible to achieve the transmission of IR spectrum radiation through it at a level of at least 95% for a radiation wavelength of 850 nm and at least 75% for a radiation wavelength of 940 nm.

The housing contains a processor printed circuit board and a lighting circuit board connected to each other by means of connectors, as well as an optical system and a scattering filter.

The processor printed circuit board provides placement of a microcontroller and a photosensitive element on it and can be made in the form of a PCB or getinax plate with a microcircuit applied to it.

The photosensitive element performs the function of an image receiver and provides its reading and transmission of the palm image to the microcontroller. The photosensitive element can be made in the form of a CMOS (CMOS) or CCD (CCD) matrix photosensitive in the IR region of the spectrum.

The microcontroller provides the implementation of the user identification algorithm based on the pattern of palm veins and can be represented as a microcircuit printed on a printed circuit board. The algorithm consists in analyzing the image of the user's palm vein pattern, identifying the user in accordance with the results of the analysis, and providing him with the required access. The optical system provides focusing of the image of the user's palm on the photosensitive element and can be represented as a lens. The lens is a cylindrical body with focusing lenses inside. The optical system can be located inside the device housing based on the processor printed circuit board, and the central axis of the optical system can be co-directed with the axis of symmetry of the matrix of the photosensitive element.

The lighting printed circuit board provides placement of LEDs on it and can be made in the form of a textolite or getinax plate with an LED power supply chip applied to it. The printed circuit board may have a cylindrical hole to accommodate an optical system inside it.

LEDs perform the function of an emitter and provide the formation of PC spectrum radiation to illuminate the user's palm. LEDs can emit light in the wavelength range from 850 to 940 nanometers. The LEDs can be arranged on the lighting circuit board in a circle around the hole for the optical system, to evenly illuminate the user's palm.

Emitter polarizers are located above the LEDs, which ensure the production of plane polarized radiation in the near PC range from the unpolarized radiation formed by the LEDs. A receiver polarizer is located above the photosensitive element, which also provides polarization in the near PC range of radiation read by the photosensitive element. The direction of radiation polarization is characterized by the light wave intensity vector, while the light wave intensity vector of the receiver polarizer is perpendicular to the light wave intensity vector of the emitter polarizers. Such a mutually perpendicular orientation of the polarization directions makes it possible to illuminate the user's palm with plane-polarized light, and when plane-polarized light is reflected from the inner layers of the palm, its polarization direction coincides with the polarization direction of the receiver polarizer. This allows the photosensitive element to fix only the light reflected from the palm veins, while minimizing the reflection of IR radiation from the surface of the user's skin and its contact with the photosensitive element, thereby increasing the contrast of the image containing the pattern of the user's palm veins.

The emitter and receiver polarizers have a multilayer structure, which ensures their protection from external influences. One of the layers of the polarizer is made in the form of a film containing a polarization grating. The polarizing grating consists of conductors that can be deposited on a translucent plastic substrate. The width of the conductors, as well as the distance between them, can vary in the range from 50 to 150 nm, which is much smaller than the wavelengths of the near-IR range (from 850 to 940 nm), and allows you to improve the optical transmission in the near-IR range, as well as increase the contrast images of palm vein pattern.

Another of the layers of the polarizer is made of a solid light-transmitting material that provides protection of the polarization grating from external influences and is located above the layer containing it. The light-transmitting material can be represented by an optical glass that provides light transmission without significant distortion. The layer containing the polarizing grating and the layer of solid light-transmitting material can be interconnected by lamination using an optical adhesive.

One of the surfaces of the layer of solid light-transmitting material of the emitter polarizer can be made light-scattering by increasing the inhomogeneity of the material surface, which makes it possible to increase the degree of radiation scattering and the uniformity of illumination of the user's palm by it. Increasing the non-uniformity of the surface of the light-transmitting material can be achieved by applying a relief pattern or roughness. In the most preferred embodiment, the non-uniformity of the surface of the light-transmitting material can be achieved by making it matte. Making the surface of the layer of the light-transmitting material matte makes it possible to reduce the size of the roughness to a size smaller than the wavelength of the incident light, thereby increasing the scattering coefficient of the radiation of the solid light-transmitting material. To impart additional rigidity to the structure of the polarizer and reduce the risk of its damage and failure, a layer containing a polarizing grating can be located between two layers of a solid light-transmitting material. The surface of each of the two layers of solid light-transmitting material can also be made light-diffusing, and in particular can be made matte, which further increases the degree of scattering of radiation coming from the emitter.

The surfaces of the layer of solid light-transmitting material of the polarizer of the receiver can be made smooth, which ensures minimal scattering of radiation incident on the receiver, thereby improving the quality of the received them images of the user's palm vein pattern, which improves the efficiency of the user's biometric identification.

The diffusion filter ensures that the radiation generated by the LEDs is scattered and allows even illumination of the user's palm. The scattering filter is installed inside the housing above the polarizers of the emitters and can have an annular structure that absorbs light from each of the LEDs.

The invention can be made from known materials using known means, which indicates its compliance with the criterion of patentability "industrial applicability".

The invention is characterized by a set of essential features previously unknown from the prior art, characterized in that one surface of the layer of solid light-transmitting material of the emitter polarizer is light-scattering, which makes it possible to increase the light scattering coefficient of the layer of solid light-transmitting material and ensure uniform illumination of the user's palm with polarized light coming from the emitters.

The set of essential features of the invention makes it possible to increase the image contrast of the user's palm vein pattern by making the receiver and emitter polarizers in such a way that their polarization directions are perpendicular to each other, which makes it possible to increase the difference between two polarized light components that are perpendicular to each other. Also, the set of essential features provides an increase in the efficiency of biometric identification of the user according to the pattern of the veins of his palm, in particular, due to the uniform illumination of the user's palm with polarized light, an increase in the area of \u200b\u200bthe palm illuminated by near-IR light occurs, which makes it possible to use for biometric identification not only those user veins that are in the center of the palm, but also those that are on the periphery with it.

This ensures the achievement of the technical result, which consists in increasing the degree of scattering of radiation coming from the emitter, thereby increasing the efficiency of the user's biometric identification.

The invention has a set of essential features previously unknown from the prior art, which indicates its compliance with the criterion of patentability "novelty". From the prior art, a device for identifying the veins of the user's palm is known, containing a series-located emitter and a polarizer of the emitter, as well as a series-located radiation receiver and a polarizer of the radiation receiver, the light wave intensity vectors of which are perpendicular to each other. Also, a device for projecting radiation is known from the prior art, containing a series of emitter polarizer emitter, which at the same time has a multilayer structure, one of the layers of which is made of a solid light-transmitting material and provides protection for the polarization grating from external influences, however, the use of this device in the field of biometric identification of users does not seem possible.

However, devices are not known from the prior art, in which the problems of increasing the protection of the polarization grating from external influences and increasing the contrast of the image of the pattern of the veins of the human palms can be simultaneously solved. Also, devices are not known in which, other things being equal, it is possible to increase the degree of scattering of radiation coming from the emitter, due to the implementation of one of the surfaces of the layer of solid light-transmitting material as light-scattering.

In view of this, the invention meets the criterion of patentability "inventive step".

The invention is illustrated by the following figures.

Fig.1 - Palm vein identification device, cross section

Fig. 2 - Scheme of the location of the LEDs on the printed circuit board of the device.

Fig. 3 - Scheme of the polarization filters inside the palm vein identification device.

Fig. 4 - The structure of the polarizing filter plate.

In order to illustrate the possibility of implementation and a better understanding of the essence of the invention, an embodiment of its implementation is presented below, which can be modified or supplemented in any way, while the present invention is by no means limited to the presented embodiment.

The palm vein identification device contains a hollow body 1, covered with a cover, which is an IR transmission filter 2. Inside the body 1, there is a processor printed circuit board 3 with a microcontroller and a photosensitive element 4 placed on it. The photosensitive element 4 is represented by a CMOS matrix sensitive in the IR region of the spectrum . An optical system is located above the photosensitive element 4, in the form of a lens 5, designed for forming an image on the CMOS matrix of the photosensitive element 4. Also inside the case contains a printed circuit board 6 lighting, with LEDs 7 of the IR spectrum placed on it. LEDs 7 are located in a circle around the lens 5. Printed circuit boards 3 and 6 are interconnected using connectors 8.

As shown in FIG. 1 and 3, polarizing filters 9 are located above the LEDs 7, and polarizing filter 10 is located above the photosensitive element 4, the light wave strength vector of which is perpendicular to the light wave strength vector of the polarizing filter 9. In this case, the polarization direction of the filters is shown by lines in Fig. 3.

Polarizing filters 9 and 10 provide polarization in the near-IR wavelength range and are made in the form of plates having a solid structure consisting of five layers. The polarizing filter 9 contains an active layer 300 made in the form of a polarizer, the polarizing layer of which consists of metal conductors and is deposited on a plastic substrate. The width of the conductors is equal to the distance between them and is 5 = 100 nm. Layers 100 and 500 are optical glasses, the outer surfaces of which are matte and perform a light-scattering function. Layers of translucent optical adhesive 200 and 400 provide lamination of the active layer 300 between two layers 100 and 500 of optical glass. The polarizing filter 10 has an identical structure, and the surface of the optical glass layers 100 and 500 is glossy.

An annular diffusing filter 11 is installed above the polarizing filters 9, which provides uniform illumination of the palm with LEDs 7.

The invention works as follows.

The user brings the palm to the identification device and fixes its position at a distance of 4-10 cm from the filter 2. The LEDs 7 form the IR spectrum radiation, which falls on the polarizing filters 9 and passing through the optical glass layer 500 is scattered by its matte surface, and then passing through the layer 400 optical adhesive falls on the active layer 300 of the polarizer. On the active layer 300 of the polarizer, the radiation polarized orthogonally to the conductors passes through them, and the rest of the radiation is reflected from their surface, and at the exit from the layer 300 the radiation has a plane polarized structure. The radiation, passing through the layer 200 of the optical adhesive, falls on the layer 100 of the optical glass, where it is additionally scattered by its matte surface and falls on the annular diffuser. filter I. Passing through the annular diffuse filter And, the radiation is scattered and the user's palm is evenly illuminated.

Plane-polarized IR radiation illuminating the user's palm passes through the skin and is absorbed to varying degrees by oxyhemoglobin and deoxyhemoglobin contained in human blood, and is also reflected from them to varying degrees. At the same time, due to the fact that IR radiation is plane polarized, it is reflected to a lesser extent from the surface of the user's palm and can be better absorbed by blood components. The radiation reflected by the blood components enters the lens 5, where an image is formed, which then enters the polarizing filter 10. The radiation reflected by the blood components is also plane polarized, however, when it is reflected from the blood components, the direction of its polarization changes. Also, the lens 5 receives not only the radiation reflected by the human blood components, but also the radiation reflected from the user's palm, the entry of which into the lens 5 is undesirable. The radiation entering the lens 5, passing through the active layer 300 of the polarizing filter 10, is polarized in the direction perpendicular to the polarization direction of the filter 9. The polarized radiation obtained at the output of the filter 10, falling on the CMOS matrix of the photosensitive element 4, forms a contrast image of the palm veins on it. After that, this image is sent to the microcontroller of the printed circuit board 3, which analyzes it and, in accordance with the results of the analysis, identifies the user and provides him with the required access.

Claims

Claim

1. The device for identifying the veins of the user's palm contains a series-located emitter and a polarizer of the emitter, as well as a series-located radiation receiver with a polarizer of the receiver, the light wave intensity vector of which is perpendicular to the light wave intensity vector of the emitter polarizer, and the emitter polarizer has a multilayer structure, with In this case, one of the layers is made in the form of a film containing a polarizing grating, and another of the layers is made of a solid light-transmitting material, characterized in that one surface of the layer of solid light-transmitting material of the emitter polarizer is made light-scattering.

2. The device according to claim 1, characterized in that the surface of the layer of solid light-transmitting material is matte.

3. The device according to claim 1, characterized in that the polarizing grating is located between two layers of solid light-transmitting material.

4. The device according to claim 3, characterized in that the surface of each of the layers of solid light-transmitting material is matte.

5. The device according to claim 1, characterized in that the polarizer of the receiver has a multilayer structure.

6. The device according to claim 5, characterized in that one of the polarizer layers of the receiver is made of a solid light-transmitting material.

7. The device according to claim 6, characterized in that the surfaces of the layer of solid light-transmitting material are smooth.

8. The device according to claim 1, characterized in that the pitch of the polarization grating is from 50 to 150 nm.