Detection System and Detection Method

Abstract

To provide an imaging device capable of non-destructively and clearly photographing residues derived from a human body.SOLUTION: An imaging device 10 comprises an infrared sensor 11, a polarizer 12, a lens 13, and a cooler 14. The infrared sensor includes at least two infrared detection elements that receive light in a wavelength band in the infrared region. Reflectance of the light obliquely incident on a medium having absorption characteristics in the wavelength band in the infrared region differs between an s wave and a p wave contained in the light. For example, a complex refractive index of infrared light differs between a medium that does not totally reflect the infrared light such as plastic and glass and a fingerprint whose main component is an organic component such as glycerate ester. By rotating the polarizer, a worker using the imaging device can adjust the polarizer so that the infrared sensor receives the light in a deflection direction that can emphasize reflection of the fingerprint more than that of the medium.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an imaging device and the like used for photographing residues derived from the human body.

Background Art

[0002] Residues (also called adherences) derived from the human body adhere to objects touched by the human body. For example, patterns such as fingerprints and palm prints of a person adhere to an object touched by the person's fingertips or hands. Residues such as fingerprints adhering to an object are difficult to visually recognize and difficult to preserve as evidence.

[0003] At a crime scene or the like, in order to preserve latent fingerprints as evidence, it is necessary to clearly record them when photographed with a visible camera. As typical methods, methods such as the aluminum powder method and the ninhydrin method are used. In the aluminum powder method, fine powder of aluminum mixed with silica, talc, kaolin, etc. is sprinkled on the object to detect fingerprints. In the ninhydrin method, fingerprints are detected by utilizing a chemical reaction in which amino acids contained in the fingerprints react with ninhydrin to turn red-violet when a chemical obtained by dissolving ninhydrin reagent in acetone or the like is sprayed on the fingerprints.

[0004] There were several problems with methods of applying powder or liquid to fingerprints, such as the aluminum powder method and the ninhydrin method. For example, in the aluminum powder method, since fine powder is applied to the object, the object and its surroundings become dirty. For example, in the ninhydrin method, since the fingerprints themselves and the objects to which the fingerprints adhere are easily damaged, it is difficult to apply in cases where there are fingerprints over a wide area.

[0005] Patent Document 1 discloses a fingerprint detection method for obtaining a latent image of a fingerprint by imaging using light in a wavelength range with a particularly high absorption rate by sebum or the like that forms the fingerprint as detection light. In the method of Patent Document 1, first image data is captured using detection light in a narrow wavelength range centered around 2,850 cm−1, which is specifically absorbed by sebum. Here, cm−1 corresponds to the number of waves per centimeter. For example, a wavelength of 2,850 cm−1 corresponds to approximately 3.5 micrometers. Further, in the method of Patent Document 1, second image data is captured using reference light in a wavelength range different from that of the detection light. Then, in the method of Patent Document 1, the first image data and the second image data are compared to visualize fingerprints that cannot be visually recognized. According to the method of Patent Document 1, fingerprints can be detected non-destructively without soiling the object or its surroundings.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] When photographing fingerprints adhering to a flat surface such as glass or metal, an image of regular reflection on the surface of sebum is mainly captured. Since the regular reflection image of the sebum component is not an image using specific absorption, the effect of narrow detection light cannot be obtained. Therefore, in the method of Patent Document 1, when photographing a flat surface such as glass or metal, the difference between the first image data captured using the detection light and the second image data captured using the reference light becomes small, making it difficult to capture clear fingerprints. Further, in the method of Patent Document 1, it has been difficult to obtain clear fingerprints due to the influence of reflection or the like by the object to which the fingerprints adhere.

[0008] An object of the present invention is to provide an imaging device or the like that can clearly photograph non-destructively residues derived from the human body.

Means for Solving the Problems

[0009] An imaging device according to one aspect of the present invention includes a polarizer having a polarization plane and an infrared sensor having at least two infrared detection elements that receive light in an infrared wavelength band that has passed through the polarizer.

[0010] A detection method according to one aspect of the present invention is a detection method using an imaging device including a polarizer having a polarization plane and an infrared sensor having at least two infrared detection elements that receive light in an infrared wavelength band that has passed through the polarizer, wherein a computer performs imaging control on the imaging device, detects a fingerprint from image data captured by the imaging device, and outputs a detection result regarding the detected fingerprint.

Effect of the Invention

[0011] According to the present invention, it becomes possible to provide an imaging device or the like that can clearly photograph non-destructively residues derived from the human body.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, although the embodiments described below have technically preferable limitations for carrying out the present invention, they do not limit the scope of the invention below. In all the drawings used in the description of the following embodiments, the same reference numerals are given to the same parts unless otherwise specified. In the following embodiments, repeated descriptions of the same configuration and operation may be omitted.

[0014] (First Embodiment) First, the imaging device of the first embodiment will be described with reference to the drawings. The imaging device of the present embodiment captures an image for detecting a residue (also called an attachment) derived from a human body. The image captured by the imaging device of the present embodiment is used for detecting a residue derived from a human body. For example, the imaging device of the present embodiment receives infrared light reflected / scattered by a residue derived from a human body. Hereinafter, fingerprints will be taken as an example to describe residues derived from a human body. For example, residues derived from a human body may be traces other than fingerprints, such as palm prints, foot prints (plantar prints), toe prints, ear prints, nose prints, and lip prints. Hereinafter, traces derived from a human body such as fingerprints, palm prints, foot prints (plantar prints), toe prints, ear prints, nose prints, lip prints, forehead prints, and jaw prints are also called patterns. Note that the detection target in the present embodiment is not limited to fingerprints, palm prints, foot prints (plantar prints), toe prints, ear prints, nose prints, lip prints, forehead prints, and jaw prints. For example, residues derived from a human body may be body fluids such as blood. For example, the detection target based on the image captured by the imaging device of the present embodiment is not limited to components included in residues derived from human contact, and there is no limitation as long as it can be detected by controlling the wavelength of infrared rays or the like.

[0015] (Configuration) FIG. 1 is a conceptual diagram showing an example of the configuration of the imaging device 10 according to the present embodiment. The imaging device 10 includes an infrared sensor 11, a polarizer 12, a lens 13, and a cooler 14. In the present embodiment, it is assumed that the range of the object to be photographed (also referred to as the photographing object range) is sufficiently bright. The imaging device 10 also has a control unit (not shown) that converts the electrical signal output by the infrared sensor 11 into image data and outputs the converted image data. In the present embodiment, the image data includes data for at least two pixels.

[0016] The infrared sensor 11 is a sensor that detects light in the wavelength band of the infrared region. The infrared sensor 11 has at least two infrared detection elements that receive light in the wavelength band of the infrared region. If there are two infrared detection elements, the presence or absence of residues can be detected according to the presence or absence of light reception in different infrared detection elements. For example, the infrared sensor 11 is composed of a one-dimensional or two-dimensional sensor in which a plurality of infrared detection elements are arranged. For example, when the purpose is to detect residues derived from the human body, the infrared sensor 11 may be composed of two infrared detection elements. Also, when detecting patterns or the like derived from human contact, it is better to configure the infrared sensor 11 as a two-dimensional sensor.

[0017] The infrared sensor 11 receives light in the wavelength band of the infrared region that enters through the polarizer 12 and the lens 13 and converts it into an electrical signal. The infrared sensor 11 outputs the converted electrical signal. For example, the infrared sensor 11 outputs an electrical signal according to the control by a control unit (not shown). The electrical signal output from the infrared sensor 11 is converted into image data by the control unit. This image data can be converted into an image for detecting residues derived from the human body in a detection device, an external system, an external device, etc., and can be displayed on a display device or the like. For example, an image based on the electrical signal output by the infrared sensor 11 is used for detecting and matching patterns such as fingerprints.

[0018] For example, the infrared sensor 11 is a sensor having a cooled infrared detection element. For example, the infrared sensor 11 has a quantum-type infrared detection element. For example, the infrared sensor 11 has an infrared detection element including sensor materials such as cadmium mercury telluride (HgCdTe), indium antimonide (InSb), gallium arsenide (GaAs), and aluminum gallium arsenide (AlGaAs). For example, the infrared sensor 11 has a quantum well-type infrared detection element including a type-II superlattice in which indium arsenide (InAs) and gallium antimonide (GaSb) are laminated. For example, the infrared sensor 11 has an infrared detection element including sensor materials such as platinum silicon (PtSi) and germanium silicon (GeSi). Note that if the infrared sensor 11 can detect residues derived from the human body such as fingerprints, it does not have to be a quantum type that does not require cooling. However, in this wavelength band, the quantum type that requires cooling is more sensitive and is often used. The infrared detection element constituting the infrared sensor 11 may be selected to include a material that is highly sensitive in the wavelength band of the detection target. For example, it is preferable that the infrared detection element constituting the infrared sensor 11 is sensitive to infrared rays in the wavelength range from the near-infrared region to the mid-infrared region (1 to 5 micrometers).

[0019] For example, the infrared sensor 11 is hermetically sealed by a sealing member having a window that transmits light in the infrared wavelength band. For example, for the window portion provided in the sealing member, a material similar to that of the lens 13 described later can be used.

[0020] For example, residues of the human body such as fingerprints are a mixture of moisture, fat, dust, etc. The main component of the fat (sebum) is a fatty acid ester compound. FIG. 2 shows an example (broken line) of the infrared absorption spectrum of the fatty acid ester compound. FIG. 2 also shows an example (solid line) of the infrared absorption spectrum of residues derived from the human body such as fingerprints. The fatty acid ester compound has infrared absorption characteristics in a wavelength band including 3.5 micrometers (within the frame of the dashed-dotted line). Therefore, as the infrared sensor 11, it is preferable to use a two-dimensional sensor including an infrared detection element having sensitivity in a wavelength band including 3.5 micrometers. When detecting residues such as fingerprints by utilizing the infrared absorption characteristics of substances other than the fatty acid ester compound, it is desirable to use a sensor including an infrared detection element having sensitivity in a wavelength band with high infrared absorption characteristics of the substance to be detected.

[0021] For example, when detecting patterns such as fingerprints formed by residues derived from the human body, the infrared sensor 11 preferably has the number of pixels capable of discriminating such patterns. For example, when detecting fingerprints, the resolution of the infrared sensor 11 is preferably configured by a two-dimensional sensor having at least 320×256 pixels. Furthermore, it is more preferable that the resolution of the infrared sensor 11 has 640×480 pixels or more. The resolution of the infrared sensor 11 is desirably determined according to the size, shape, state, etc. of the detection target.

[0022] The polarizer 12 has a polarization plane. The polarizer 12 selectively passes linearly polarized light having a polarization plane in a specific direction. The polarizer 12 is disposed on the light receiving surface side of the infrared sensor 11. The polarizer 12 is installed facing all the infrared detection elements included in the infrared sensor 11. The polarizer 12 aligns the polarization direction of the incident light in one direction. The light whose polarization direction is aligned by the polarizer 12 is incident on the light receiving surface of the infrared sensor 11.

[0023] For example, the polarizer 12 has a structure in which a polarizer that selectively transmits linearly polarized light is fixed within a frame. For example, the frame of the polarizer 12 can be of any shape such as circular, elliptical, square, rectangular, polygonal, etc. However, when the polarizer 12 is housed inside the housing of the imaging device 10, the frame of the polarizer 12 is preferably a point-symmetric shape like a circle for convenience of rotation within a limited space. For example, when the infrared sensor 11 is vacuum-sealed by a sealing member, the function of the polarizer 12 may be added to the window portion of the sealing member. In that case, the window portion of the sealing member and the polarizer 12 may be integrated.

[0024] The polarizer 12 is installed rotatably about the imaging axis P of the infrared sensor 11 as the central axis. The polarizer 12 is rotated about the imaging axis P as the central axis. For example, the polarizer 12 has a structure that can be rotated from the outside of the imaging device 10 via a rotation member (not shown). For example, an operator using the imaging device 10 manually rotates the polarizer 12. For example, the polarizer 12 may be configured to rotate in response to rotation control by a control device (not shown).

[0025] The lens 13 is a lens that can focus infrared rays in the wavelength band of the detection target. The lens 13 focuses the infrared rays in the wavelength band of the detection target onto the light-receiving surface of the infrared sensor 11. For example, for the lens 13, lenses made of materials such as germanium (Ge), silicon (Si), zinc sulfide (ZnS), zinc selenide (ZnSe), sapphire (Al2O3), etc. can be used. For example, for the lens 13, lenses made of materials such as barium fluoride (BaF2), calcium fluoride (CaF2), lithium fluoride (LiF), chalcogenide glass, etc. can be used. Any lens that can focus infrared rays in the wavelength band of the detection target may be used for the lens 13. For example, it is preferable that the lens 13 is equipped with an autofocus function.

[0026] The cooler 14 is a device for cooling the infrared sensor 11. In FIG. 1, the infrared sensor 11 is in contact with the cooler 14. For quantum-type infrared sensors, the cooler 14 is necessary to exclude the influence of noise caused by dark current and the like. For example, the cooler 14 cools the infrared sensor 11 so that the temperature ranges from about 60 to 250 Kelvin. If it is not necessary to cool the infrared sensor 11, the cooler 14 may be omitted. For example, as the cooler 14, a cooler having a Stirling mechanism or an electronic cooling element using the Peltier effect is used.

[0027] FIG. 3 is a conceptual diagram showing an example of detecting the fingerprint 110 attached to the object 100 using the imaging device 10. First, the imaging device 10 is arranged with the imaging axis P aligned with the object 100 where a fingerprint is presumed. At this time, the imaging direction of the imaging device 10 is set in a fixed state such as a jig or in a state held by an operator. Then, the imaging device 10 captures an image of the object 100 where a fingerprint 110 is presumed in a state where the imaging direction is set according to the operation of the operator. If the fingerprint 110 is attached to the object 100, an image including the fingerprint 110 corresponding to the polarization direction of the polarizer 12 is captured. For example, the operator rotates the polarizer 12 to adjust it so that the fingerprint 110 becomes clear. For example, the imaging device 10 may be provided with a display unit for displaying the image captured by the infrared sensor imaging device 10. If the display unit is provided in the imaging device 10, it becomes easier for the operator using the imaging device 10 to check the image when the polarizer 12 is rotated.

[0028] The reflectance of light obliquely incident on a medium having absorption characteristics in the wavelength band of the infrared region is different between the s-wave and p-wave contained in the light. For example, the complex refractive index of infrared rays is different between a medium that does not totally reflect infrared rays such as plastic and glass, and a fingerprint mainly composed of an organic component such as glyceric acid ester. The operator using the imaging device 10 can adjust the polarizer 12 so that the light in the polarization direction that can emphasize the reflection of the fingerprint 110 more than the medium is received by the infrared sensor 11 by rotating the polarizer 12.

[0029] FIG. 4 is a conceptual diagram showing an example of a detection state of a fingerprint detected according to the polarization direction of the polarizer 12. In the case of the polarization direction A, most of the polarized light reflected by the fingerprint 110 is blocked by the polarizer 12. Therefore, in the case of the polarization direction A, the fingerprint 110 is not clearly detected. On the other hand, in the case of the polarization direction B, most of the polarized light reflected by the fingerprint 110 passes through the polarizer 12. Therefore, in the case of the polarization direction B, the fingerprint 110 is clearly detected.

[0030] 〔Modification Example〕 Here, a modification example of the imaging device 10 of the present embodiment will be exemplified. The following modification examples are merely examples and do not limit the modification examples of the imaging device 10 of the present embodiment.

[0031] FIG. 5 is a conceptual diagram showing an example of the configuration of the imaging device 10-1 of Modification Example 1. The imaging device 10-1 is configured to install the polarizer 12 outside the lens 13 of the imaging device 10 in FIG. 1. If the polarizer 12 is installed outside the lens 13 as in Modification Example 1, it becomes easier for an operator using the imaging device 10-1 to manually rotate the polarizer 12.

[0032] FIG. 6 is a conceptual diagram showing an example of the configuration of the imaging device 10-2 according to Modification 2. The imaging device 10-2 is configured to dispose a filter 15 outside the lens 13 of the imaging device 10 in FIG. 1. The filter 15 is a filter that selectively passes light in the wavelength band of the detection target. For example, when detecting a residue such as a fatty acid ester compound resulting from the attachment of a human body, a filter that selectively passes infrared light in a wavelength band including 3.5 micrometers may be used for the filter 15. By using a filter that selectively passes light in the wavelength band derived from the residue of the detection target, the residue of the detection target can be selectively detected. Note that since the wavelength band of the detection target varies depending on the type of the residue, it is preferable to make the filter 15 replaceable according to the wavelength band of the detection target. For example, the filter 15 may be a combination of a plurality of filters having different optical characteristics. According to Modification 2, by using the filter 15 that selectively passes light in the wavelength band of the detection target, light in the wavelength band derived from a residue such as a fingerprint can be selectively received, so that the fingerprint or the like of the detection target can be detected more clearly.

[0033] As described above, the imaging device of the present embodiment includes a polarizer having a polarization plane and an infrared sensor having at least two infrared detection elements that receive light in the infrared wavelength band that has passed through the polarizer. According to the present embodiment, by detecting light in the infrared wavelength band that has passed through the polarizer, a residue derived from a human body can be clearly photographed nondestructively.

[0034] In one aspect of the present embodiment, the polarizer is rotatable about the imaging axis of the infrared sensor. In one aspect of the present embodiment, the infrared detection element has sensitivity to light in the wavelength band of 1 to 5 micrometers. In one aspect of the present embodiment, a filter that selectively passes light in a wavelength band including 3.5 micrometers is provided on the light receiving surface side of the infrared sensor.

[0035] An operator using the imaging device of the present embodiment photographs an object on which residues are presumed to be attached while rotating a polarizer. The reflectance of light obliquely incident on a medium having absorption characteristics in the infrared wavelength band differs between the s-wave and p-wave contained in the light. For example, the complex refractive index of infrared rays differs between a medium that does not totally reflect infrared rays, such as plastic or glass, and a fingerprint mainly composed of an organic component such as glyceric acid ester. In the present embodiment, by rotating the polarizer, the polarizer is adjusted to a deflection angle at which the reflection of the fingerprint can be emphasized more than that of the medium. As a result, according to the present embodiment, residues such as fingerprints can be clearly photographed nondestructively.

[0036] For example, fingerprints attached to a flat surface such as glass can be detected even with visible light. On the other hand, fingerprints attached to a non-flat surface such as wood or plastic cannot be detected with visible light. The light reflected from a non-flat surface contains a mixture of specular reflection and diffuse reflection. Diffuse reflection cannot be detected with visible light. In the method of the present embodiment, since diffuse reflection can also be received using light in the infrared wavelength band, residues derived from the human body can be clearly detected.

[0037] The method of the present embodiment can also be applied to the use of determining the presence or absence of attachment of residues. For example, by using the method of the present embodiment, if the difference between an image in which residues can be clearly detected and an image in which residues cannot be detected is taken, the residues can be detected more clearly. Further, the method of the present embodiment can be applied not only to fingerprints but also to the detection of palm prints, foot prints, and the like.

[0038] (Second Embodiment) Next, a detection system according to the second embodiment will be described with reference to the drawings. The detection system of the present embodiment includes an illumination device for facilitating the detection of residues derived from the human body such as fingerprints. In the present embodiment, a phenomenon in which the visibility of residues changes depending on the relative angle formed by the polarization direction of the polarizer of the imaging device and the polarization direction of the polarizer of the illumination device is utilized.

[0039] FIG. 7 is a conceptual diagram showing an example of the configuration of the detection system 2 of the present embodiment. The detection system 2 includes an imaging device 20 and an illumination device 25. FIG. 7 is an example of detecting a fingerprint 210 attached to an object 200 using the imaging device 20. In the example of FIG. 7, the imaging device 20 detects the reflected light of the polarized light 271 emitted from the illumination device 25.

[0040] Generally, residues such as fingerprints are very thin, so the amount of infrared absorption is small. Therefore, when photographing residues such as fingerprints attached to a flat surface such as glass or metal, it may be difficult to detect an image associated with the absorption of the residue more than expected. Therefore, it is easier to obtain a clearer image by setting to actively utilize the Fresnel reflection image. The reason why the Fresnel reflection image can be seen is that the refractive index of the surface of the glass or plastic medium is different from the refractive index of residues such as fingerprints, so the Brewster angles are different. Therefore, it is preferable that the light emitted from the illumination device 25 is irradiated at the Brewster angle with respect to the adhesion surface of the residue. If polarized light is irradiated at the Brewster angle with respect to the surface to which residues such as fingerprints are attached, the p-polarized light is not reflected, so only the s-polarized light can be guided to the imaging device 20. Even if the light emitted from the illumination device 25 is unpolarized, if the light is irradiated at the Brewster angle, it becomes completely polarized light.

[0041] The imaging device 20 includes at least an infrared sensor 21 and a polarizer 22. The illumination device 25 includes a light source 26 and a polarizer 27. The imaging device 20 is the same as the imaging device 10 of the first embodiment. Therefore, in the following, the description of the imaging device 10 will be simplified, and the illumination device 25 will be described focusing thereon.

[0042] The light source 26 is illumination for facilitating the detection of residues derived from the human body. For example, the light source 26 emits infrared light (near-infrared to mid-infrared) in a wavelength range including 1 to 5 micrometers. For example, as the light source 26, a filament of an incandescent bulb that operates at a low temperature in the temperature range of 100 to 1000 degrees Celsius, such as silicon carbide (SiC) or nichrome (NiCr), can be used. For example, if such a filament is operated at around 1000 degrees Celsius, infrared light in the wavelength range including 1 to 5 micrometers can be emitted with a watt-class output. Note that the filament used for the light source 26 is not limited to silicon carbide (SiC) or nichrome (NiCr) as long as it can emit infrared light in the wavelength band of the detection target. For example, if a milli-watt-class output is sufficient, a light-emitting diode may be used as the light source 26.

[0043] The polarizer 27 (also referred to as the illumination-side polarizer) is an element that selectively allows linearly polarized light in a specific direction to pass through. The polarizer 27 polarizes the light emitted from the light source 26 into linearly polarized light. The polarized light that has passed through the polarizer 27 is irradiated toward the object 200 where residues derived from the human body are presumed to be present.

[0044] 〔Modification Example〕 Here, a modification example of the detection system 2 of the present embodiment will be exemplified. The following modification examples are merely examples and do not limit the modification examples of the detection system 2 of the present embodiment.

[0045] FIG. 8 is a conceptual diagram showing an example of the configuration of the detection system 2-1 according to Modification 1 of the present embodiment. The detection system 2-1 is an example in which the imaging device 20 and the illumination device 25 included in the detection system 2 of FIG. 7 are housed inside a single housing. In the detection system 2-1, the emission axis of the polarized light 271 emitted from the illumination device 25 and the imaging axis of the imaging device 20 are made non-parallel. In this modification, since the emission axis of the polarized light 271 emitted from the illumination device 25 and the imaging axis of the imaging device 20 are fixed, the direction (imaging direction) in which the reflected light of the polarized light 271 reflected from the surface of the object 200 enters the imaging device 20 becomes constant. Therefore, according to this modification, stable detection becomes possible. Further, according to this modification, since the imaging device 20 and the illumination device 25 can be integrated, it becomes easier for the operator to carry the detection system 2-1.

[0046] As described above, the detection system of the present embodiment includes an imaging device and an illumination device. The illumination device emits light in the wavelength band of the detection target of the infrared detection element included in the imaging device. In one aspect of the present embodiment, the illumination device includes a light source that emits light in the wavelength band of the detection target of the infrared detection element, and an illumination-side polarizer that selectively passes linearly polarized light having a polarization plane in a specific direction among the light emitted from the light source.

[0047] The detection system of the present embodiment can illuminate an object on which residues of the detection target are presumed to be attached with the illumination device. Therefore, according to the detection system of the present embodiment, even in a dark working environment with insufficient external light, residues derived from the human body can be detected clearly and non-destructively.

[0048] When shooting by combining a general infrared camera and a general infrared lamp, the external environment such as the reflection image of the infrared lamp is likely to be reflected in the infrared camera. In the present embodiment, residues such as fingerprints are photographed while rotating the polarization direction of the polarizer incorporated in the imaging device. In the present embodiment, by adjusting the polarization direction of the polarizer to an appropriate angle, a clearer fingerprint image can be photographed than when there is no polarizer.

[0049] (Third Embodiment) Next, a detection system according to a third embodiment will be described with reference to the drawings. The detection system of this embodiment includes a detection device that detects fingerprints using image data output by an imaging device.

[0050] FIG. 9 is a conceptual diagram showing an example of the configuration of the detection system 3 of this embodiment. The detection system 3 includes an imaging device 30, an illumination device 35, and a detection device 330. FIG. 9 shows an example of detecting a fingerprint 310 attached to an object 300 using the imaging device 30. In the example of FIG. 9, the imaging device 30 detects the reflected light of the polarized light 371 emitted from the illumination device 35.

[0051] The imaging device 30 includes at least an infrared sensor 31 and a polarizer 32. The illumination device 35 includes a light source 36 and a polarizer 37. The imaging device 30 is the same as the imaging device 10 of the first embodiment. Also, the illumination device 35 is the same as the imaging device 20 of the second embodiment. In the following, the description of the imaging device 30 and the illumination device 35 will be simplified, and the description will focus on the detection device 330.

[0052] The detection device 330 is connected to the imaging device 30. The detection device 330 may be connected to the imaging device 30 by wire or wirelessly. Also, the detection device 330 may be connected to the imaging device 30 via a network (not shown). The detection device 330 may be configured as a dedicated server device or terminal device, or may be realized by software installed in a general-purpose server device or terminal device.

[0053] The detection device 330 controls the imaging of the imaging device 30 and the rotation of the polarizer 32. The detection device 330 controls the imaging of the imaging device 30 and causes the imaging device 30 to capture the imaging target range. The detection device 330 detects the portion derived from the fingerprint from the image of the imaging target range captured by the imaging device 30. For example, the detection device 330 extracts features from the image of the imaging target range and determines whether the features are derived from the fingerprint based on the size and shape of the range where the features are extracted, the state and density of the lines included in the range, etc. When features derived from the fingerprint are not detected, the detection device 330 controls the rotation of the polarizer 32 to change the polarization direction of the polarized light incident on the infrared sensor 31.

[0054] For example, when the detection device 330 detects features derived from the fingerprint, it controls the rotation of the polarizer 32 to identify the polarization direction in which the fingerprint is clearly detected. When the detection device 330 identifies the polarization direction in which the fingerprint is clearly detected, it generates an image (also called a fingerprint image) for detecting the fingerprint using the image data captured in that polarization direction. Among the functions of the detection device 330, the function of controlling the rotation of the polarizer 37 and the function of generating the fingerprint image may be integrated into the main body of the infrared camera. For example, by integrating with a system for fingerprint verification via a network, the detection device 330 can be used portably.

[0055] The detection device 330 outputs the detection result regarding the detected fingerprint. For example, the detection device 330 outputs the fingerprint image in the polarization direction in which the fingerprint 310 is most clearly captured. The fingerprint image is used for verification using the fingerprint, etc. Note that if the detection device 330 can identify the fingerprint, it may also output an image in which the fingerprint 310 is not most clearly captured as the fingerprint image. The fingerprint image output from the detection device 330 may be output to a display device (not shown) or to a system that performs fingerprint verification, etc. using the fingerprint image.

[0056] 〔Imaging Device〕 Next, an example of the configuration of the imaging device 30 will be described with reference to the drawings. FIG. 10 is a conceptual diagram showing an example of the configuration of the imaging device 30. The imaging device 30 includes a rotating member 320 in addition to an infrared sensor 31, a polarizer 32, and a lens 33. Note that the imaging device 30 may include a cooler for cooling the infrared sensor 31.

[0057] The rotating member 320 is a member that rotates the polarizer 32. For example, the rotating member 320 can be realized by a gear that meshes with teeth formed on the outer periphery of the circular polarizer 32 to rotate the polarizer 32. When the polarizer 32 is realized by a gear, the polarizer 32 can be rotated by controlling the rotation of a motor (not shown) with the center of the gear as the rotation axis. The rotating member 320 rotates in accordance with the rotation control of the detection device 330. When the rotating member 320 rotates, the polarizer 32 rotates, and the polarization direction of the polarized light incident on the infrared sensor 31 is changed. Note that the structure and shape of the rotating member 320 are not particularly limited as long as the polarizer 32 can be rotated. Also, the driving method of the rotating member 320 is not limited to a motor as long as the polarizer 32 can be rotated.

[0058] When the angle formed by the polarization direction of the polarizer 32 of the imaging device 30 and the polarization direction of the polarizer 37 of the illumination device 35 is orthogonal, the fingerprint 310 is not detected. On the other hand, when the angle formed by the polarization direction of the polarizer 32 of the imaging device 30 and the polarization direction of the polarizer 37 of the illumination device 35 is 0 degrees or 45 degrees, the fingerprint 310 is more easily detected. By taking the difference between an image with an angle of 0 degrees (45 degrees) and an image with an angle of 90 degrees with respect to the polarization direction of the polarizer 37 of the illumination device 35, the fingerprint 310 is more easily detected. Therefore, the detection device 330 may detect the fingerprint 310 from the difference between an image with an angle of 0 degrees (45 degrees) and an image with an angle of 90 degrees with respect to the polarization direction of the polarizer 37 of the illumination device 35.

[0059] 〔Detection Device〕 FIG. 11 is a block diagram showing an example of the configuration of the detection device 330. The detection device 330 includes a polarization direction control unit 331, an imaging control unit 332, an image processing unit 333, and a detection unit 334.

[0060] The polarization direction control unit 331 controls the rotation of the rotating member 320 in accordance with an instruction from the detection unit 334. When the rotating member 320 rotates according to the rotation control of the polarization direction control unit 331, the polarizer 32 rotates. Further, the polarization direction control unit 331 may be configured to rotate the polarizer 32 clockwise or counterclockwise at a fine rotation angle in accordance with an instruction to finely adjust the rotation of the polarizer 32.

[0061] The imaging control unit 332 controls the imaging of the imaging device 30. The imaging control unit 332 outputs the image data captured in accordance with the imaging control to the image processing unit 333.

[0062] The image processing unit 333 acquires the image data from the imaging control unit 332. The image processing unit 333 performs image processing on the acquired image data to generate detection data (also referred to as a fingerprint image) for detecting feature amounts. For example, the image processing unit 333 performs at least any one of image processing such as dark current correction, interpolation calculation, color space conversion, gamma correction, aberration correction, noise reduction, and image compression on the image data. Note that the image processing by the image processing unit 333 is not limited to that listed here. Also, if image processing is not necessary, the image processing unit 333 may be omitted. The image processing unit 333 outputs the generated detection data to the detection unit 334.

[0063] The detection unit 334 acquires the detection data from the image processing unit 333. The detection unit 334 detects a fingerprint from the acquired detection data. The detection unit 334 outputs a detection result regarding the detected fingerprint. Further, the detection unit 334 may output an instruction to finely adjust the rotation of the polarizer 32 to the polarization direction control unit 331 in order to obtain a clearer fingerprint image.

[0064] FIG. 12 shows an example in which an image (fingerprint image 311) of the fingerprint 310 detected by the detection device 330 is displayed on the display device 340. For example, an operator compares the fingerprint image 311 displayed on the display device 340 with a fingerprint image (also referred to as reference fingerprint data) stored in a database (not shown) or the like to collate the fingerprints. For example, the display device 340 may display the time, location, situation, etc. when the fingerprint 310 from which the fingerprint image 311 is extracted was detected, instead of the fingerprint image 311. For example, the display device 340 may display the time, location, situation, etc. when the fingerprint 310 from which the fingerprint image 311 is extracted was detected simultaneously with the fingerprint image 311.

[0065] (Operation) Next, the operation of the detection device 330 will be described with reference to the drawings. FIG. 13 is a flowchart for explaining the operation of the detection device 330. In FIG. 13, the detection device 330 will be described as the main body of the operation.

[0066] In FIG. 13, first, the detection device 330 controls the imaging of the imaging device 30 and causes the imaging device 30 to image a range where it is estimated that the fingerprint 310 is attached (step S31).

[0067] Next, the detection device 330 processes the captured image data to generate detection data (step S32).

[0068] When the detection device 330 detects a fingerprint from the detection data (Yes in step S33), it outputs a detection result regarding the fingerprint (step S35).

[0069] On the other hand, when no fingerprint is detected from the detection data (No in step S33), the detection device 330 controls the rotation of the polarizer 32 to change the polarization direction (step S34). After step S34, it returns to step S31.

[0070] As described above, the detection system of the present embodiment includes an imaging device, an illumination device, and a detection device. The detection device performs imaging control on the infrared sensor of the imaging device and rotation control on the polarizer included in the imaging device. The detection device detects residues derived from a human body from the image data captured by the infrared sensor imaging device and outputs a detection result regarding the detected residues. In one aspect of the present embodiment, when the detection device detects a fingerprint to be collated, it rotates the polarizer to adjust the polarization direction of the polarizer, thereby specifying the polarization direction in which the fingerprint to be collated is clearly photographed.

[0071] According to the present embodiment, residues derived from a human body can be detected from the image captured by the imaging device. According to the present embodiment, by the detection device controlling the imaging device and the illumination device, it is also possible to automatically detect residues derived from a human body.

[0072] (Fourth Embodiment) Next, the detection system according to the fourth embodiment will be described with reference to the drawings. The detection system of the present embodiment includes a detection device that searches a database storing fingerprint data of a plurality of persons and collates the fingerprint detected from the image captured by the imaging device.

[0073] FIG. 14 is a conceptual diagram showing an example of the configuration of the detection system 4 of the present embodiment. The detection system 4 includes an imaging device 40, an illumination device 45, a detection device 430, and a database 450. In the database 450, fingerprint data of a plurality of persons (also referred to as reference fingerprint data) used for fingerprint collation is stored. FIG. 14 is an example of detecting the fingerprint 410 attached to the object 400 using the imaging device 40. In the example of FIG. 14, the imaging device 40 detects the reflected light of the polarized light 471 emitted from the illumination device 45.

[0074] The imaging device 40 has at least an infrared sensor 41 and a polarizer 42. The lighting device 45 has a light source 46 and a polarizer 47. The imaging device 40 is the same as the imaging device 10 of the first embodiment. Also, the lighting device 45 is the same as the imaging device 20 of the second embodiment. In the following, the description of the imaging device 40 and the lighting device 45 will be simplified, and the description will focus on the detection device 430.

[0075] The detection device 430 is connected to the imaging device 40. The detection device 430 may be connected to the imaging device 40 by wire or wirelessly. Also, the detection device 430 may be connected to the imaging device 40 via a network (not shown). The detection device 430 may be configured as a dedicated server device or terminal device, or may be realized by software installed in a general-purpose server device or terminal device. Also, the detection device 430 may be integrated with the imaging device 40. For example, functions such as rotation control of the polarizer 42 may be integrated into the imaging device 40, and functions such as fingerprint matching and image analysis may be performed by accessing the database 450 via the cloud. In such a case, the detection device 430 is realized in the form of a dedicated mobile terminal having an information processing function and a communication function, or in the form of software installed in a general-purpose mobile terminal such as a notebook computer or a smartphone.

[0076] The detection device 430 performs imaging control of the imaging device 40 and rotation control of the polarizer 42. The detection device 430 performs imaging control of the imaging device 40 and causes the imaging device 40 to photograph the imaging target range. The detection device 430 detects a portion derived from a fingerprint from the image of the imaging target range photographed by the imaging device 40. For example, the detection device 430 extracts features from the image of the imaging target range, and determines whether the features are derived from a fingerprint based on the size and shape of the range where the features are extracted, the state and density of the lines included in the range, and the like. If features derived from a fingerprint are not detected, the detection device 430 controls the rotation of the polarizer 42 to change the polarization direction of the polarized light incident on the infrared sensor 41.

[0077] For example, when the detection device 430 detects a feature derived from a fingerprint, it controls the rotation of the polarizer 42 to identify the polarization direction in which the fingerprint is clearly detected. When the detection device 430 identifies the polarization direction in which the fingerprint is clearly detected, it generates an image (also referred to as a fingerprint image) for detecting the fingerprint using the image data captured in that polarization direction.

[0078] When the detection device 430 detects a fingerprint (also referred to as a fingerprint to be matched) from the fingerprint image, it extracts feature points from the fingerprint to be matched. The detection device 430 searches the database 450 and detects a reference fingerprint having feature points with a high degree of match with the feature points of the fingerprint to be matched. The detection device 430 outputs a matching result regarding the fingerprint to be matched.

[0079] 〔Detection Device〕 FIG. 15 is a block diagram showing an example of the configuration of the detection device 430. The detection device 430 includes a polarization direction control unit 431, an imaging control unit 432, an image processing unit 433, a detection unit 434, a feature point extraction unit 435, and a matching unit 436. The polarization direction control unit 431, the imaging control unit 432, the image processing unit 433, and the detection unit 434 are the same as the configurations included in the detection device 330 of the third embodiment. Therefore, hereinafter, the description will focus on the feature point extraction unit 435 and the matching unit 436 that are not included in the detection device 330 of the third embodiment.

[0080] The feature point extraction unit 435 acquires the fingerprint (also referred to as a fingerprint to be matched) detected by the detection unit 434. The feature point extraction unit 435 extracts feature points from the acquired fingerprint to be matched. The feature point extraction unit 435 outputs the extracted feature points to the matching unit 436. For example, the feature point extraction unit 435 extracts positions such as the starting point of a ridge line, an island-shaped line (island line), an independent short ridge line (short ridge line), the ending point of a ridge line, a junction point where ridge lines are connected, a branching point where ridge lines split, and other points as feature points.

[0081] The matching unit 436 acquires the feature points extracted by the feature point extraction unit 435. The matching unit 436 searches the database 450 and detects a reference fingerprint having feature points with a high degree of match with the feature points of the fingerprint to be matched. The matching unit 436 outputs a matching result regarding the fingerprint to be matched. For example, the matching unit 436 outputs identification information such as the name of the individual associated with the reference fingerprint detected by the matching, and personal information as the matching result.

[0082] Alternatively, the matching unit 436 may acquire the fingerprint to be matched from the detection unit 434 and search the database 450 for a reference fingerprint having a high degree of match with the fingerprint to be matched. Then, the matching unit 436 compares the feature points of the retrieved reference fingerprint with the feature points of the fingerprint to be matched, and may determine that they are matched if a preset matching determination criterion is satisfied. For example, the matching unit 436 compares the matched reference fingerprint with the feature points of the reference fingerprint and calculates the degree of match. For example, the matching unit 436 compares a plurality of feature points and calculates the ratio (degree of match) of the matching feature points. Further, the matching unit 436 may perform matching based on the shape of the ridge lines, the shape, interval / position of the sweat pores on the ridge lines, etc.

[0083] FIG. 16 is an example of displaying the matching result by the detection device 430 on the screen of the display device 440. In the example of FIG. 16, the name (AAA) of the individual associated with the reference fingerprint detected by the matching is displayed on the screen of the display device 440 as the matching result. The operator can recognize the person of the fingerprint to be matched by referring to the matching result displayed on the screen of the display device 440.

[0084] (Operation) Next, the operation of the detection device 430 will be described with reference to the drawings. FIG. 17 is a flowchart for explaining the operation of the detection device 430. In FIG. 17, the detection device 430 will be described as the main body of the operation.

[0085] In FIG. 17, first, the detection device 430 controls the imaging of the imaging device 40 and causes it to image a range where it is estimated that the fingerprint 410 is attached (step S41).

[0086] Next, the detection device 430 performs image processing on the captured image data to generate detection data (step S42).

[0087] When a fingerprint is detected from the detection data (Yes in step S43), the detection device 430 extracts feature points from the fingerprint (step S45).

[0088] On the other hand, when no fingerprint is detected from the detection data (No in step S43), the detection device 430 controls the rotation of the polarizer 42 to change the polarization direction (step S44). After step S44, the process returns to step S41.

[0089] Next to step S45, the detection device 430 searches the database 450 and performs fingerprint matching to detect a reference fingerprint having feature points with a high degree of match with the feature points of the fingerprint to be matched (step S46).

[0090] Then, the detection device 430 outputs the matching result (step S47).

[0091] As described above, the detection system of the present embodiment includes an imaging device, an illumination device, and a detection device. The infrared sensor included in the imaging device has a number of pixels capable of identifying patterns formed by residues derived from the human body. The detection device detects a reference pattern formed by residues from the image data captured by the imaging device, and extracts feature points from the detected reference pattern. The detection device of the present embodiment searches a database storing reference patterns of a plurality of persons used for pattern matching, and detects a reference pattern having feature points with a high degree of match with the feature points of the reference pattern to be matched. The detection device of the present embodiment outputs a matching result regarding the reference pattern to be matched.

[0092] The matching result of the detection system of the present embodiment can be applied to a system for identifying a person by pattern matching. Further, the matching result of the detection system of the present embodiment can also be applied to services such as tracking along the identified pattern.

[0093] (Fifth Embodiment) Next, the imaging device according to the fifth embodiment will be described with reference to the drawings. The imaging device of this embodiment has a simplified configuration compared to the imaging devices of the first to fourth embodiments.

[0094] FIG. 18 is a block diagram showing an example of the configuration of the imaging device 50 of this embodiment. The imaging device 50 includes an infrared sensor 51 and a polarizer 52. The polarizer 52 has a polarization plane. The infrared sensor 51 has at least two infrared detection elements that receive light in the wavelength band of the infrared region that has passed through the polarizer.

[0095] As described above, the imaging device of this embodiment includes a polarizer having a polarization plane and an infrared sensor having at least two infrared detection elements that receive light in the wavelength band of the infrared region that has passed through the polarizer. According to this embodiment, by detecting the light in the wavelength band of the infrared region that has passed through the polarizer, residues derived from the human body can be clearly photographed non-destructively.

[0096] (Hardware) Here, the hardware configuration for executing the processing of the detection device according to each embodiment of the present invention will be described by taking the information processing device 90 in FIG. 19 as an example. Note that the information processing device 90 in FIG. 19 is an example of a configuration for executing the processing of the detection device of each embodiment, and does not limit the scope of the present invention.

[0097] As shown in FIG. 19, the information processing device 90 includes a processor 91, a main storage device 92, an auxiliary storage device 93, an input / output interface 95, and a communication interface 96. In FIG. 19, the interface is abbreviated as I / F (Interface). The processor 91, the main storage device 92, the auxiliary storage device 93, the input / output interface 95, and the communication interface 96 are connected to be able to communicate with each other via a bus 98. Also, the processor 91, the main storage device 92, the auxiliary storage device 93, and the input / output interface 95 are connected to a network such as the Internet or an intranet via the communication interface 96.

[0098] The processor 91 expands the program stored in the auxiliary storage device 93 or the like into the main storage device 92 and executes the expanded program. In the present embodiment, a configuration using the software program installed in the information processing apparatus 90 may be employed. The processor 91 executes the processing by the detection apparatus according to the present embodiment.

[0099] The main storage device 92 has an area where the program is expanded. The main storage device 92 may be a volatile memory such as a DRAM (Dynamic Random Access Memory), for example. Further, a non-volatile memory such as an MRAM (Magnetoresistive Random Access Memory) may be configured and added as the main storage device 92.

[0100] The auxiliary storage device 93 stores various data. The auxiliary storage device 93 is constituted by a local disk such as a hard disk or a flash memory. Note that it is also possible to configure to store various data in the main storage device 92 and omit the auxiliary storage device 93.

[0101] The input / output interface 95 is an interface for connecting the information processing apparatus 90 and peripheral devices. The communication interface 96 is an interface for connecting to an external system or apparatus through a network such as the Internet or an intranet based on standards and specifications. The input / output interface 95 and the communication interface 96 may be made common as an interface for connecting to external devices.

[0102] The information processing apparatus 90 may be configured to connect input devices such as a keyboard, a mouse, and a touch panel as necessary. Those input devices are used for inputting information and settings. When the touch panel is used as an input device, the display screen of the display device may also serve as the interface of the input device. Data communication between the processor 91 and the input device may be mediated by the input / output interface 95.

[0103] Further, the information processing apparatus 90 may be provided with a display device for displaying information. When providing a display device, it is preferable that the information processing apparatus 90 is provided with a display control device (not shown) for controlling the display of the display device. The display device may be connected to the information processing apparatus 90 via the input / output interface 95.

[0104] The above is an example of the hardware configuration for enabling the detection device according to each embodiment of the present invention. Note that the hardware configuration in FIG. 19 is an example of the hardware configuration for executing the arithmetic processing of the detection device according to each embodiment, and does not limit the scope of the present invention. Also, a program for causing a computer to execute the processing related to the detection device according to each embodiment is included in the scope of the present invention. Furthermore, a recording medium recording the program according to each embodiment is included in the scope of the present invention. The recording medium can be realized by, for example, an optical recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc). Also, the recording medium may be realized by a semiconductor recording medium such as a USB (Universal Serial Bus) memory or an SD (Secure Digital) card, a magnetic recording medium such as a flexible disk, or other recording media. When the program executed by the processor is recorded on the recording medium, the recording medium corresponds to a program recording medium.

[0105] The components of the detection device according to each embodiment can be arbitrarily combined. Also, the components of the detection device according to each embodiment may be realized by software or by a circuit.

[0106] As described above, the present invention has been described with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

Explanation of Reference Numerals

[0107] 2, 3, 4 Detection System 10, 20, 30, 40 Imaging Devices 11, 21, 31, 41, 51 Infrared Sensors 12, 22, 32, 42, 52 Polarizers 13, 33 Lenses 14 Coolers 15 Filters 25, 35, 45 Lighting Devices 26, 36, 46 Light Sources 27, 37, 47 Polarizers 50 Imaging Device 320 Rotating Member 330, 430 Detection Devices 331, 431 Polarization Direction Control Units 332, 432 Imaging Control Units 333, 433 Image Processing Units 334, 434 Detection Units 340, 440 Display Devices 435 Feature Point Extraction Unit 436 Matching Unit 450 Database

Claims

1. A polarizer having a polarization plane, An imaging device comprising: an infrared sensor having at least two infrared detection elements that receive light in an infrared wavelength band that has passed through the polarizer, An illumination device, Comprising, The illumination device is configured to irradiate light in the wavelength band to be detected by the infrared detection element at a predetermined angle with respect to the adhesion surface of the human body residue, The imaging device is configured to receive s-polarized light reflected by the human body residue among the light irradiated from the illumination device from an oblique direction with respect to the adhesion surface, The imaging device, A detection system.

2. The polarizer is rotatable about the imaging axis of the infrared sensor. The detection system according to claim 1.

3. The imaging device captures a Fresnel reflection image of the residue. The detection system according to claim 1 or 2.

4. The predetermined angle is the Brewster angle with respect to the adhesion surface. The detection system according to claim 1 or 2.

5. The illumination device, A light source that emits light in the wavelength band to be detected by the infrared detection element, An illumination-side polarizer that selectively passes linearly polarized light having a polarization plane in a specific direction among the light emitted from the light source. The detection system according to any one of claims 1 to 4.

6. A detection device that performs imaging control on the imaging device and rotation control on the polarizer, The detection device, Detects the residue derived from the human body from the image data captured using the imaging device, Outputs a detection result regarding the detected residue. The detection system according to any one of claims 1 to 5.

7. The detection device, Detects a collation target pattern formed by the residue from the image data captured using the infrared sensor, Extracts feature points from the detected collation target pattern, Searches a database storing collation patterns of a plurality of persons used for fingerprint collation, Detects the collation pattern having feature points with a high degree of coincidence with the feature points of the collation target pattern, Outputs a collation result regarding the collation target pattern. The detection system according to claim 6.

8. When the detection device detects the collation target pattern, the detection device rotates the polarizer to adjust the polarization direction of the polarizer, thereby specifying the polarization direction in which the collation target pattern is clearly captured. The detection system according to claim 7.

9. [[ID=400 ​ ​ An imaging device comprising a polarizer having a polarization plane and an infrared sensor having at least two infrared detection elements that receive light in the infrared wavelength band that has passed through the polarizer, and a detection method in a detection system comprising an illumination device, wherein: the illumination device is: arranged so as to be able to irradiate light in the wavelength band of the detection target of the infrared detection element onto the adhesion surface of the human body residue at a predetermined angle; the imaging device is: arranged so as to be able to receive s-polarized light reflected by the human body residue among the light irradiated from the illumination device from an oblique direction with respect to the adhesion surface; a computer: performs imaging control on the imaging device; detects fingerprints from the image data captured by the imaging device; A detection method for outputting a detection result regarding the detected fingerprint.

Images