Palm prosthesis suitable for infrared detection

Abstract

A palm prosthesis suitable for infrared detection is characterized in that the palm prosthesis comprises a skin imitation body which has a scattering effect on infrared light; the vein imitation body is located in the skin imitation body; and the surface film layer is positioned on the surface of the skin imitation body and is provided with textures. According to the invention, through imaging, a vein imaging effect close to that of a real palm can be realized, and the vein imaging effect of an optical system can be quantitatively evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of palm detection, and in particular to a palm prosthesis suitable for infrared detection. Background Art

[0002] As an emerging biometric technology, palm vein recognition has been widely promoted due to its non-contact, high anti-counterfeiting and high precision. In palm vein recognition technology, the quality of vein imaging is particularly critical. However, the vein features are distributed inside the palm, and the light reflected from the palm surface is likely to interfere with the vein imaging and superimpose image noise; therefore, it is usually considered to introduce polarized light imaging to filter out the light reflected from the palm surface and suppress noise. Among them, the polarization performance of the imaging system is also directly related to the final vein imaging effect, so a set of objective evaluation equipment is urgently needed to evaluate the polarization imaging performance of the system.

[0003] For palm detection, RGB cameras are often used to collect palm print images, or infrared cameras are used to collect subcutaneous palm vein images, or both types of cameras are used for collection. However, the existing vein prosthesis solutions are somewhat different from real palm veins and cannot simulate the collection process of cameras using RGB cameras or infrared cameras. In addition, the evaluation effect of the vein imaging performance of the palm vein imaging system is limited. Some improvements need to be made on this basis to optimize the phantom.

[0004] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0005] To this end, the present invention uses a skin phantom, a vein phantom and a surface film layer to simulate the palm state during non-contact detection. By imaging the invention, a vein imaging effect close to that of a real palm can be achieved, and the vein imaging effect of the optical system can be quantitatively evaluated to address the deficiencies in the prior art.

[0006] The present invention provides a palm prosthesis suitable for infrared detection, which is characterized by comprising:

[0007] Skin phantom, which has a scattering effect on infrared light;

[0008] A vein phantom, located within the skin phantom;

[0009] The surface film layer can transmit infrared light, is fixed on the surface of the skin phantom, and has texture.

[0010] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the skin phantom is made of silicone or latex.

[0011] Optionally, the palm prosthesis suitable for infrared detection is characterized in that at least two points of the vein phantom are at different distances from the surface of the skin phantom.

[0012] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the vein phantom includes a first vein phantom and a second vein phantom; the first vein phantom and the second vein phantom have different widths.

[0013] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the first vein phantom and the second vein phantom are at different distances from the surface of the skin phantom.

[0014] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the surface film layer is low-density polyethylene resin, low-density polypropylene resin, low-density polyurethane or other low-density synthetic materials.

[0015] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the texture of the surface film layer is formed by pressing.

[0016] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the transmittance of the surface film layer to infrared light is not less than 30%.

[0017] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the vein phantom can absorb infrared light, and the infrared band reflectivity of the vein phantom is different from the infrared band reflectivity of the skin phantom.

[0018] Optionally, the palm prosthesis suitable for infrared detection is characterized in that the distance between the vein phantom and the surface of the skin phantom is [5mm, 8mm].

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] In the present invention, the vein phantom is arranged in the skin phantom, and the skin phantom has a scattering effect on infrared light, which can well simulate the process of infrared light penetrating the skin and irradiating the vein, and the vein imaging simulation is higher.

[0021] The surface film layer in the present invention is arranged on the surface of the skin phantom, has specific reflectivity and transmittance in the infrared light band, and has texture; it can well simulate the noise interference caused by the palm prints on the skin surface reflecting infrared light imaging and the process of infrared light penetrating the surface skin into the subcutaneous tissue; it can well simulate the image noise caused by the surface palm prints in palm vein imaging.

[0022] The present invention standardizes the detection of the imaging system and can quantitatively evaluate the imaging performance and polarization performance of the imaging system.

[0023] The present invention does not require manual experience judgment when testing, and can be performed quantitatively, so that the vein imaging effect evaluation of the palm vein imaging system is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings in the following descriptions are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without creative work. By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present invention will become more obvious:

[0025] Figure 1 This is a schematic diagram of the structure of a palm prosthesis suitable for infrared detection in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of polarization camera detection in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of imaging a palm prosthesis by a non-polarized optical system according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the imaging effect of a palm prosthesis by a polarized optical system according to an embodiment of the present invention;

[0029] Figure 5 is a grayscale distribution curve of vein positions of a palm prosthesis imaged by a non-polarized optical system in an embodiment of the present invention;

[0030] Figure 6 This is a grayscale distribution curve of vein positions of a palm prosthesis imaged by a polarized optical system in an embodiment of the present invention.

[0031] 1- Infrared transmitter;

[0032] 2- Infrared receiving end;

[0033] 3-Parallel polarizers;

[0034] 4-vertical polarizer;

[0035] 5-Surface film layer;

[0036] 6-Venous phantom;

[0037] 7-Skin phantom; DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0039] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein, for example, can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] The embodiment of the present invention provides a palm prosthesis suitable for infrared detection, aiming to solve the problems existing in the prior art.

[0041] The following specific embodiments are used to describe in detail the technical solutions of the present invention and how the technical solutions of the present application solve the above-mentioned technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0042] In the present invention, the vein phantom is arranged in the skin phantom, and the skin phantom has a scattering effect on infrared light, which can well simulate the process of infrared light penetrating the skin and irradiating the vein, and the vein imaging simulation is higher; in the present invention, the surface film layer is arranged on the surface of the skin phantom, has a specific reflectivity and transmittance in the infrared light band, and has a texture, which can well simulate the reflection of the palm surface and the infrared light penetrating the skin into the subcutaneous tissue.

[0043] Figure 1FIG. 1 is a schematic diagram of the structure of a palm prosthesis suitable for infrared detection in an embodiment of the present invention. Figure 1 As shown, in an embodiment of the present invention, a palm prosthesis suitable for infrared detection includes:

[0044] The skin phantom 7 has a scattering effect on infrared light.

[0045] Specifically, the skin phantom is the main structure of the palm prosthesis, which mainly simulates the skin characteristics of a real human palm. It has a scattering effect on infrared light, which is to simulate the performance of real skin under infrared light, so that the palm prosthesis can present similar characteristics to the real palm in infrared detection. In order to achieve the scattering effect of infrared light, the skin phantom is usually made of a material with scattering characteristics. Since only palm prints and vein information under the skin are usually collected when the palm is detected, this embodiment does not need to completely simulate the structure of the palm, but only needs to simulate the epidermis and part of the subcutaneous tissue. The skin phantom in this embodiment has a certain thickness, which is greater than the depth that the infrared light can penetrate.

[0046] The vein phantom 6 is located inside the skin phantom.

[0047] Specifically, the vein phantom is located inside the skin phantom and mainly simulates the venous network inside the real palm. It is one of the most critical parts of the palm prosthesis because vein recognition technology mainly relies on the recognition of the venous network. It should be noted that the vein phantom is used to simulate the characteristics of the vein, but it does not need to simulate the distribution and direction of the vein. The absorption and reflection characteristics of the vein phantom to infrared light are different from those of the skin phantom, so that a clear venous image can be presented under infrared light. At the same time, these materials also need to have good stability and durability to ensure that they will not change when used for a long time or exposed to different environments.

[0048] The surface film layer 5 can transmit infrared light, is fixed on the surface of the skin phantom, and has a texture.

[0049] Specifically, the surface film layer allows infrared light to penetrate, and the surface film layer has a higher transmittance to infrared light than the skin phantom. The surface film layer has fine textures that mimic the texture characteristics of real palm skin. Texture can simulate the reflection characteristics of real palms in infrared detection. Different reflectivity and texture characteristics of the film layer will lead to different reflection effects, thus affecting the final infrared image. Texture can also be used to detect the shooting effect of RGB cameras.

[0050] In some embodiments, the skin phantom is silicone or latex. Silicone is a highly elastic synthetic material with good flexibility and durability. Silicone has a moderate scattering effect on infrared light and can simulate the performance of real skin under infrared light. Studies have shown that as the concentration of glycerol increases, the scattering coefficient of silicone decreases, which helps to increase the light penetration depth, so a suitable silicone with a scattering coefficient can be selected according to the intensity of the tested infrared light. Silicone is easy to process into various shapes and sizes, suitable for the manufacture of complex structures, such as palm prostheses containing fine vascular structures. Silicone skin phantoms are excellent in wear resistance and aging resistance and have a long service life. Latex is a natural or synthetic rubber material with certain elasticity and softness. The scattering effect of latex on infrared light may vary depending on the material formula and process, so it is necessary to select a formula and process with suitable scattering characteristics. Latex materials are relatively cheap and suitable for large-scale production and application. Silicone skin phantoms are generally superior to latex skin phantoms in terms of wear resistance and aging resistance. The production cost of latex skin phantoms is relatively low, and they are suitable for large-scale production and application; however, silicone skin phantoms are more expensive due to the high material cost and processing complexity. Both silicone and latex are safe and non-toxic materials.

[0051] In some embodiments, the vein phantom has at least two points with different distances from the surface of the skin phantom. The vein phantom in the palm prosthesis is not a simple planar structure, but has a three-dimensional shape and a complex layout. This means that different parts (i.e., different points or areas) in the vein phantom are at different distances from the surface of the skin phantom. This design can simulate the depth variation of the veins in the real palm, thereby increasing the realism and recognition accuracy of the prosthesis under infrared detection. The vein phantom is usually made of materials with specific absorption characteristics, such as anhydrous copper sulfate, etc., which can simulate the absorption effect of real veins on infrared light. In the design of the vein phantom, there will be at least two points (or areas) with different distances from the skin surface. This means that in some parts, the vein phantom will be closer to the skin surface, while in other parts it will be relatively deep. This design can simulate the different depths of the veins in the real palm, because in the actual palm, the depth of the veins will also vary due to individual differences. By making the vein phantom different from the skin surface, a more realistic palm vein structure can be simulated. In infrared detection, vein recognition technology relies on the accurate recognition of the venous vascular network. The three-dimensional shape and distance differences of the vein phantom help to conduct more comprehensive testing. If the vein phantom is a simple planar structure or all points are the same distance from the surface of the skin phantom, it will be difficult to simulate the vein characteristics of the real palm, thus reducing the comprehensiveness of the test.

[0052] In some embodiments, the vein phantom includes a first vein phantom and a second vein phantom; the first vein phantom and the second vein phantom have different widths. This embodiment simulates the diversity of veins in a real palm. The venous network of a real palm is composed of veins of different widths and depths. By setting different widths for the vein phantom, this diversity can be simulated more accurately, thereby increasing the realism and credibility of the prosthesis. The vein phantom is composed of at least two parts, namely the first vein phantom and the second vein phantom. The two parts simulate different vein areas in a real palm respectively. The first vein phantom and the second vein phantom have different widths. This design can simulate the width variation of veins in a real palm, because in an actual palm, the width of veins in different parts will also be different. Due to the differences in the palm vein characteristics of different people, including the width, depth and distribution of veins, etc. By setting different widths for the vein phantom, it can be more adapted to the palm characteristics of different people, thereby improving the versatility and adaptability of the prosthesis.

[0053] In some embodiments, the first vein phantom and the second vein phantom are at different distances from the surface of the skin phantom. The venous network of a real palm has a complex three-dimensional layout, and different veins are located at different depth levels. By setting different depths (i.e., distances from the surface of the skin phantom) for the first vein phantom and the second vein phantom, the sense of hierarchy and depth of the real vein structure can be more accurately simulated. In infrared detection, vein recognition technology relies on the accurate recognition of the venous network. Vein phantoms of different depths help infrared detection equipment to capture and identify vein features more accurately.

[0054] In some embodiments, the surface film layer is low-density polyethylene, low-density polypropylene, low-density polyurethane or other low-density synthetic materials. Low-density polyethylene (LDPE) is a soft, translucent plastic material with good chemical resistance and electrical insulation. It can be processed into films, pipes and products of various shapes by methods such as blow molding, extrusion and injection molding. Due to its excellent flexibility and low-temperature resistance, LDPE is often used to make plastic bags, agricultural films and food packaging materials. In addition, it can also be used for insulating layers of wires and cables and products such as artificial leather. Low-density polypropylene (LDPP) is a thermoplastic resin with good heat resistance, chemical resistance and mechanical strength. Compared with LDPE, LDPP has a higher melting point and hardness. Low-density polyurethane (LDPU) is a polymer generated by the reaction of isocyanate groups and polyols, with good elasticity and wear resistance. It can be made into hard or soft foam plastics. In addition to the above three common low-density synthetic materials, there are many other types of low-density synthetic materials, such as polystyrene (PS), polycarbonate (PC) and polyamide (PA). These materials each have their own characteristics and can be selected and applied according to specific needs.

[0055] In some embodiments, the texture of the surface film layer is formed by pressing. In the design of palm prosthesis, the texture of the surface film layer is very important for simulating the appearance of real skin and the effect on infrared light. The texture formed by pressing can give the surface film layer a specific pattern, concave-convex feeling or roughness, making it more realistic and durable. The process of pressing texture usually involves placing the surface film layer material between molds or rollers, and then applying a certain pressure and temperature. The mold or roller is engraved with a specific texture pattern. When the material is subjected to pressure and temperature, it will deform according to the shape of the mold or roller, thereby forming a texture corresponding to the mold or roller. Through the precisely designed mold or roller, a texture very similar to real skin can be produced, including details such as pores, wrinkles, fingerprints, etc. The texture formed by pressing usually has high wear resistance and tear resistance, and can resist wear and tear in daily use. The pressing process can usually be automated, which can greatly improve production efficiency and reduce production costs.

[0056] In some embodiments, the transmittance of the surface film layer to infrared light is not less than 30%. When the transmittance of the surface film layer to infrared light is not less than 30%, it can ensure that the infrared light can effectively penetrate the surface film layer, interact with the internal vein phantom or other structures, and thus be accurately captured and identified by the infrared detection equipment. The transmittance of the surface film layer to infrared light can be 30%, 35%, 40%, 45%, 50% or any other unlisted values. The surface film layer with a specific transmittance can ensure that the infrared light reaches the internal vein phantom, while also having the surface texture reflection imaging effect; thereby improving the accuracy of palm vein imaging simulation.

[0057] In some embodiments, the vein phantom is capable of absorbing infrared light, and the reflectivity of the vein phantom in the infrared band is different from the reflectivity of the skin phantom in the infrared band. Vein phantoms are usually made of materials with specific optical properties that can effectively absorb infrared light and have different effects on the infrared band than skin phantoms. By precisely controlling the composition and surface treatment of the materials, the absorption rate of the vein phantom to infrared light can be adjusted to simulate the optical behavior of real veins at different wavelengths. The vein phantom can absorb infrared light and help generate infrared images similar to real veins. This absorption characteristic can improve the authenticity and recognition accuracy of the prosthesis under infrared detection, especially when using transmission infrared imaging technology. In order to achieve effective infrared absorption, the vein phantom needs to use materials with high absorption rates, such as specific plastics or metal coatings.

[0058] In some embodiments, the distance between the vein phantom and the surface of the skin phantom is [5mm, 8mm]. In a real palm, the depth of the vein is not fixed, but has a certain range of variation. This depth variation helps to distinguish different individuals and increases the security of biometric identification. By setting the vein phantom within the range of 5mm to 8mm, the vein depth variation similar to that of a real palm can be simulated, thereby improving the authenticity and recognition accuracy of the prosthesis under infrared detection.

[0059] In some embodiments, the surface film layer is a polyethylene foam film (also known as an EPE pearl cotton film); it is made of low-density polyethylene grease through physical foaming to produce countless independent bubbles, and then a texture is added to the surface through a pressing process to simulate the optical effect of the palm surface skin. The surface film layer is attached to the skin phantom through the film coating process.

[0060] In some embodiments, the vein phantom is circular or oval in shape to better simulate the characteristics of a vein.

[0061] Figure 2 This is a schematic diagram of a polarization camera detection in an embodiment of the present invention. The non-polarized light emitted by the infrared transmitting end 1 is converted into linearly polarized light after passing through the parallel polarizer 3; based on the characteristics of palm vein imaging, when the linearly polarized light hits the palm surface, the reflected light is still parallel polarized light, and after entering a certain depth of the palm, it is depolarized due to multiple scattering, and the light reflected after hitting the vein position is unpolarized light.

[0062] After the linear polarized light passes through the parallel polarizer 3, after hitting the surface film layer 5, part of the light is directly reflected by the film layer and still maintains the parallel polarization property; while the other part of the light enters the skin phantom 7, hits the vein phantom 6 and is reflected, and this part of the reflected light is depolarized and loses polarization. Here, the surface film layer of the vein phantom 5 is low-density polyethylene or other materials; the vein phantom 6 is two pre-buried metal materials of different thicknesses and different pre-buried depths to simulate the palm veins of different thicknesses and depths of the real palm; the skin phantom 7 is made of silicone material, which has a scattering effect on infrared light and is used to simulate the palm skin. The reflected light after passing through the vein phantom 6 reaches the vertical polarizer 4. At this time, the reflected light reflected by the surface film layer 5 cannot pass because of its vertical direction, while the reflected light reflected by the vein phantom 6 can pass. After passing through the vertical polarizer 4, the polarized light enters the receiving end 2, and at this time, the receiving end receives the vein signal inside the vein phantom.

[0063] By using the palm prosthesis in this embodiment, the palm veins can be imaged in the infrared band, and the polarization performance of the imaging system can be effectively detected.

[0064] At the same time, based on the acquired vein images, the vein contrast calculation can be used to quantitatively evaluate the vein imaging effect.

[0065] The following description uses two vein phantoms as an example for explanation, but those skilled in the art will appreciate that the number of vein phantoms can be any number, and any number of vein phantoms is within the protection scope of the present invention.

[0066] right Figure 3 and Figure 4 Analyze the venous prosthesis images of the two images, draw a line segment across the two veins at the same position in the two images, and draw a grayscale distribution curve on the line segment;

[0067] like Figure 6 As shown, it can be seen that the two veins correspond to Figure 6 There are two valley values ​​in the middle; and for the imaging at the same position of the prosthesis, Figure 5 Veins are almost indistinguishable in non-polarized optical systems, while polarized optical systems can image veins more clearly.

[0068] Calculate and analyze the contrast between the two veins at this location:

[0069] Contrast=(I_max-I_min) / (I_max+I_min)

[0070] Among them, I_max is the gray value of the background area, and I_min is the gray value of the vein position;

[0071] After the non-polarized optical system images the vein prosthesis, the contrast of both veins is close to 0; in the polarized optical system, the contrast of the left vein is 13.51%, and the contrast of the right vein is 29.90%. The higher the contrast, the better the corresponding vein imaging effect can be considered, which is conducive to the subsequent extraction of vein features.

[0072] By imaging the venous phantom, the venous contrast can be quantitatively calculated and the polarization performance of the polarization-type venous imaging system can be quantitatively evaluated.

[0073] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will comply with the widest range consistent with the principles and novel features disclosed herein.

[0074] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A palm prosthesis suitable for infrared detection, characterized in that: include: Skin phantom, which has a scattering effect on infrared light; A vein phantom, located within the skin phantom; The surface film layer can transmit infrared light, is fixed on the surface of the skin phantom, and has texture.

2. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: The skin phantom is made of silicone or latex.

3. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: At least two points of the vein phantom have different distances from the surface of the skin phantom.

4. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: The vein phantom includes a first vein phantom and a second vein phantom; the first vein phantom and the second vein phantom have different widths.

5. The palm prosthesis suitable for infrared detection according to claim 4, characterized in that: The first vein phantom and the second vein phantom are at different distances from the surface of the skin phantom.

6. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: The surface film layer is low-density polyethylene resin, low-density polypropylene resin, low-density polyurethane or other low-density synthetic materials.

7. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: The texture of the surface film layer is formed by pressing.

8. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: The transmittance of the surface film layer to infrared light is not less than 30%.

9. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: The vein phantom can absorb infrared light, and the infrared reflectivity of the vein phantom is different from the infrared reflectivity of the skin phantom.

10. The palm prosthesis suitable for infrared detection according to claim 1, characterized in that: The distance between the vein phantom and the surface of the skin phantom is [5mm, 8mm].

Images