The application concerned is related to a biological information obtaining device, a biological information obtaining method, and a wearable device.
In recent years, in order to guarantee the information security of mobile information devices, the biological authentication technology that makes use of biological information, such as fingerprint pattern images and vein pattern images, is becoming increasingly significant. At the same, there is advancement in the technological development of mobile information devices, and measures are being taken to make the mobile information devices thinner. Accordingly, also regarding biological information obtaining devices that obtain biological information mentioned above, there is a demand for achieving downsizing and thinning.
In that regard, in Patent Literature 1 mentioned below, a technology has been proposed in which thinning of an imaging device is attempted by installing a light focusing/shielding element, which includes two lens arrays and a single aperture array, at a stage prior to a light detecting element.
Patent Literature 1: Japanese Patent Application Laid-open No. 2011-203792
In the case of attempting further thinning of a biological imaging device; the light guiding path, which guides the light constituting biological information such as fingerprint pattern images or vein pattern images to an imaging device, becomes shorter in length by necessity. When the light guiding path becomes shorter in length, it becomes more likely to have the occurrence of stray light. At the same time, when a biological imaging device is further downsized, there is no alternative but to shorten the lens pitch of the lens array as used in Patent Literature 1 mentioned above, and it becomes more likely to have the occurrence of stray light due to the shortening of the lens pitch. In this way, in the case of attempting further downsizing and thinning of a biological imaging device, it becomes more likely to have the occurrence of stray light due to the abovementioned two factors.
In view of the issues mentioned above, in the application concerned, a biological information obtaining device, a biological information obtaining method, and a wearable device are proposed that enable holding down the occurrence of stray light to a greater extent even in the case of attempting further downsizing and thinning of the device.
According to the present disclosure, a biological information obtaining device is provided that includes: an image sensor in which biological information, which represents image information obtained as a result of emitting light of predetermined wavelength with respect to one part of a living body, is imaged; a lens array that is positioned in between the image sensor and the one part of the living body, has a plurality of single lenses arranged in an array-like manner, and performs imaging of the biological information in the image sensor; and a light shield that is positioned in between the image sensor and the lens array, and forms a light guiding path meant for imaging of the biological information, which is transmitted through each of the single lenses, in the image sensor, wherein the light guiding path is formed to have unequal opening diameter along surface normal direction of the image sensor.
Moreover, according to the present disclosure, a biological information obtaining method is provided that includes performing imaging of biological information, which represents image information obtained as a result of emitting light of predetermined wavelength with respect to one part of a living body, using a lens array, which has a plurality of single lenses arranged in an array-like manner, in an image sensor via a light guiding path formed by a light shield, wherein the light guiding path is formed to have unequal opening diameter along surface normal direction of the image sensor.
Moreover, according to the present disclosure, a wearable device is provided that includes: a device main body that is wearable by user; and a biological information obtaining device that is installed in the device main body, wherein the biological information obtaining device includes an image sensor in which biological information, which represents image information obtained as a result of emitting light of predetermined wavelength with respect to one part of a living body, is imaged, a lens array that is positioned in between the image sensor and the one part of the living body, has a plurality of single lenses arranged in an array-like manner, and performs imaging of the biological information in the image sensor, and a light shield that is positioned in between the image sensor and the lens array, and forms a light guiding path meant for imaging of the biological information, which is transmitted through each of the single lenses, in the image sensor, and the light guiding path is formed to have unequal opening diameter along surface normal direction of the image sensor.
According to the application concerned, the biological information passes through the lens array and via the light guiding paths, and is imaged in the image sensor. At that time, since the light guiding paths are formed to have unequal opening diameters, the occurrence of stray light is held down.
As described above, according to the application concerned, the occurrence of stray light can be held down to a greater extent even in the case of attempting further downsizing and thinning of devices.
The abovementioned effect is not necessarily limited in scope and, in place of or in addition to the abovementioned effect, any other effect indicated in the present written description or any other effect that may occur from the present written description can also be achieved.
A preferred embodiment of the application concerned is described below in detail with reference to the accompanying drawings. In the present written description and the drawings, the constituent elements having practically identical functional configuration are referred to by the same reference numerals, and the explanation is not given repeatedly.
The explanation is given in the following sequence.
1. Embodiment
<Regarding Structure of Biological Information Obtaining Device>
Firstly, explained below in detail with reference to
The biological information obtaining device according to the present embodiment is a device for obtaining biological information that represents image information obtained as a result of irradiating one part of a living body with the light having a predetermined wavelength. Although there is no particular restriction on the biological information, examples thereof include image information related to fingerprints (for example, fingerprint pattern images indicating the distribution of the fingerprints); image information related to perspiration (for example, images indicating the presence or absence of perspiration); image information related to blood flow; image information related to pulse wave or pulsation; and image information related to blood vessels (for example, vein pattern images indicating the distribution of veins).
The biological information obtaining device according to the present embodiment is not only capable of obtaining one type of such variety of biological information, but is also capable of simultaneously obtaining a plurality of types of biological information. The type of biological information to be obtained can be arbitrarily selected by appropriately adjusting the wavelength of the light to be emitted onto one part of the living body or adjusting the type of the part of the living body from which the image information is to be obtained. As a result, different types of biological information can be obtained in combination, such as obtaining the biological information related to fingerprints in combination with the biological information related to perspiration. Moreover, when the biological information obtained by the biological information obtaining device is to be used in various known biological authentication technologies, the authentication can be performed by combining different types of biological information, so that the authentication accuracy can be further enhanced.
As schematically illustrated in
The lens array 20 is configured by arranging a plurality of single lenses 203 in an array-like manner on a predetermined base member 201; and performs imaging of the biological information, which is transmitted through the single lenses 203, in the pixels provided in the image sensor 10. As schematically illustrated in
Meanwhile, in addition to the configuration illustrated in
Moreover, for example, as illustrated in
Given below is the detailed explanation of each constituent element of the biological information obtaining device 1 according to the present embodiment.
[Regarding Image Sensor 10]
On that surface of the image sensor 10 which is facing the lens array 20, a plurality of pixels of the image sensor 10 is arranged; and the concerned surface functions as the sensor surface of the image sensor 10. The biological information obtained from the living body LB is imaged as a result of the imaging performed on the sensor surface of the image sensor 10, and substantive image data related to the biological information is generated.
As long as the image sensor 10 is an imaging device configured with pixels having sensitivity with respect to the wavelength of the light constituting the biological information, it is possible to use any known type of imaging device. Examples of such an imaging device include a CCD (Charge Coupled Devices) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor. Meanwhile, the image sensor 10 according to the present embodiment can either be a color sensor or be a monochromatic sensor.
The pixels constituting the image sensor 10 desirably have the pixel size that enables taking images of objects having the line width in the range of a few μm to a few hundred μm. If p[μm] represents the size of the photographic subject (for example, one part of a living body, such as fingerprints or veins) and if M represents the magnification of the single lenses 203 included in the lens array 20, then p×M[μm] becomes the size of the photographic subject on the sensor surface. The pixels constituting the image sensor 10 desirably have such a pixel size which enables expressing the size of the photographic subject on the sensor surface with two or more pixels. Examples of such a pixel size include the pixel size in the range of 1 μm2 to 4 μm2. However, the pixel size in the image sensor 10 according to the present embodiment is not limited to that example.
Since the pixels constituting the image sensor 10 have the pixel size that enables taking images of objects having the line width in the range of a few μm to a few hundred m; it becomes possible to generate biological information having the resolution of 1000 PPI (Pixel Per Inch) or more, for example. Meanwhile, regarding the pixels constituting the image sensor 10, smaller the pixel size, the higher is the possibility of generating high-definition biological information. Hence, it is desirable to have a small pixel size as much as possible. Also regarding the resolution of the generated biological information, since it is desirable to have high-definition resolution as much as possible, the upper limit value of the resolution is not particularly specified.
[Regarding Lens Array 20]
As explained earlier, the lens array 20 has a plurality of single lenses 203 arranged in an array-like manner on the predetermined base member 201. The lens array 20 is also called a microlens array.
Regarding the material used for the base member 201 and the single lenses 203, as long as it is possible to transmit the light constituting the biological information, there is no particular restriction on the material and any material usable as the material for optical devices can be used. Examples of such material include various types of resin such as thermoplastic resin or thermosetting resin typified by acrylic resin, polycarbonate resin, or polyolefin resin; and various types of optical glass. Such material can be subjected to molding, pattern embossing, or lithography according to a known method; and the desired shape of the lens array can be achieved.
There is no particular restriction on the lens shape of the single lenses 203, and it is possible to have spherical single lenses 203 or aspherical single lenses 203.
In the lens array 20 according to the present embodiment, regarding the lens diameter of the single lenses 203 (a length LS with reference to
As illustrated in
If the lens diameter LS of the single lenses 203 illustrated in
In order to ensure that overlapping occurs as explained with reference to
The distance from the sensor surface of the image sensor 10 to one part of the living body LB (i.e., a distance A with reference to
Meanwhile, each single lens 203 that constitutes the lens array 20 as explained above can be a lens group configured by combining a plurality of lenses. Moreover, it is also possible to install an objective lens in between the lens array 20 and the living body LB representing the photographic subject.
[Regarding Light Shields 30]
As explained earlier, the light shields 30 are positioned in between the image sensor 10 and the lens array 20, and form light guiding paths meant for forming images of the biological information in the image sensor 10. Regarding the material of the light shields 30, there is no particular restriction, and at least either various metals such as stainless steel, or various resin composition materials, or various dielectric substances including silicon can be used.
In the biological information obtaining device 1 according to the present embodiment, as schematically illustrated in
That is, as illustrated in
More specifically, the opening diameter D is desirably equal to or greater than twice the wavelength of the light constituting the biological information, and is desirably equal to or smaller than four times the lens diameter LS of the single lenses 203. If the opening diameter D is smaller than twice the wavelength of the light, then it becomes more likely to have a diffraction phenomenon of the light in the light guiding paths, and noise is likely to get superimposed on the biological information converted into images in the image sensor 10. On the other hand, if the opening diameter is greater than four times the lens diameter LS of the single lenses 203, it is likely to have an increase in the stray light falling in the light guiding paths. Thus, within the range in which the abovementioned conditions are satisfied, the opening diameter D of the light guiding path can be varied in various ways along the surface normal direction of the image sensor 10 (i.e., along the z-axis direction).
However, if the opening diameter D of the light guiding paths is reduced to be smaller than the lens diameter LS of the single lenses 203, it not only becomes possible to exclude the effect of the end portions of such single lenses 203 which are likely to have declined in lens characteristics, but it also becomes easier to hold down the stray light coming from the neighboring light guiding paths. That enables achieving improvement in the obtained image quality. On the other hand, if the opening diameter D of the light guiding path becomes small, although it results in the narrowing of the angle of view, it becomes important to shorten the center-to-center distance (what is called the lens pitch) of the neighboring single lenses 203 for the purpose of overlapping images in the neighboring single lenses 203. Hence, at the time of manufacturing the lens array 20 having a narrow lens pitch, a higher degree of accuracy is sometimes demanded. In that context, the opening diameters D of the light guiding paths are desirably set to be equal to or greater than 0.5 times the lens diameter LS of the single lenses 203. When the opening diameters D of the light guiding paths are greater than the lens diameter LS of the single lenses 203, the amount of overlapping also increases. At the same time, when the opening diameters D of the light guiding paths are greater than the lens diameter LS of the single lenses 203, the effect of the end portions of such single lenses 203 which are likely to have declined in lens characteristics becomes conspicuous, and there is an increase in the possibility that stray light falls from the neighboring light guiding paths. That leads to a demand for making the light shields 30 thinner, and a higher degree of accuracy is sometimes demanded. In that context, the opening diameters D of the light guiding paths are more desirably set to be equal to or greater than 0.5 times the lens diameter LS of the single lenses 203 and equal to or smaller than four times the lens diameter LS of the single lenses 203.
In the biological information obtaining device 1 according to the present embodiment, the light path length of the light guiding paths formed by the pair of neighboring light shields 30 (i.e., a length L1 with reference to
As illustrated in
When the light shields 30 are cut parallel to the surface normal direction of the image sensor 10 (i.e., parallel to the z-axis direction), the outside shape of the light shields 30 facing the light guiding paths can be formed either by straight lines or by curved lines as illustrated in
Explained below in brief with reference to specific examples illustrated in
According to the present embodiment, as illustrated in the top left portion of
Alternatively, the light shields 30 facing the light guiding paths can have the outside shape as a concave shape or a convex shape as illustrated in the top right portion of
Meanwhile, the outside shape of the light shields 30 is not limited to the examples illustrated in
In
As illustrated in
As illustrated in
Moreover, in the present embodiment, on the outer surfaces of the light shields 30 facing the light guiding paths, for example, it is possible to perform a variety of regular reflection prevention processing such as forming minute uneven shapes, or performing plating with a metal having a predetermined surface roughness. As a result of performing such regular reflection prevention processing, it becomes possible to reliably reduce the stray light reaching the image sensor 10, and to obtain higher-definition biological information. Meanwhile, if the absorber 301 is disposed as well as regular reflection prevention processing is performed; it becomes possible to further reliably reduce the stray light reaching the image sensor 10, and to obtain still higher-definition biological information.
In the explanation given above, for example, as illustrated in
[Regarding Second-Type Light Shields 40]
Explained below in detail with reference to
In the biological information obtaining device 1 according to the present embodiment, as illustrated in
In an identical manner to the light shields 30, the second-type light shields 40 too can be formed using at least either various metals such as stainless steel, or various resin composition materials, or various dielectric substances including silicon.
Although there is no particular restriction on the height of the second-type light shields 40 (i.e., a length L2 in the z-axis direction with reference to
Moreover, it is desirable that the second-type light guiding paths, which are formed due to the pairs of neighboring second-type light shields 40, have an opening diameter D′ set to be greater than but close to the lens diameter LS of the single lenses 203 (i.e., D′>LS holding true). If the opening diameter D′ of the second-type light guiding paths is equal to the lens diameter LS of the single lenses 203, it sometimes becomes difficult to achieve overlapping that was explained earlier. At the same time, closer the opening diameter D′ of the second-type light guiding paths to the lens diameter LS of the single lenses 203, the more it becomes possible to further reliably prevent incidence of stray light onto the single lenses 203.
[Regarding Cover Glass 50]
As illustrated in
Regarding the material used for the cover glass 50, as long as it is possible to transmit the light constituting the biological information, there is no particular restriction on the material, and any material usable as the material for optical devices can be used. Examples of such material include various types of resin such as thermoplastic resin or thermosetting resin typified by acrylic resin, polycarbonate resin, or polyolefin resin; and various types of optical glass. However, from the perspective of strength and impact resistance, it is desirable to form the cover glass 50 using various types of resin.
Regarding the thickness of the cover glass 50, there is no particular restriction and the thickness can be appropriately set.
In
[Regarding Light Source Units 60]
As schematically illustrated in
The count and the arrangement of the light source units 60 is not limited to the example illustrated in FIG. 6, and can be appropriately set according to the size of the part to be measured in the living body LB and the size of the biological information obtaining device 1. Moreover, the arrangement positions of the light source units 60 are not limited to the positions illustrated in
Till now, detailed explanation was given with reference to
<Regarding Method for Manufacturing Biological Information Obtaining Device 1>
Regarding the method for manufacturing the biological information obtaining device 1 according to the present embodiment, there is no particular restriction. Thus, the biological information obtaining device 1 according to the present embodiment can be manufactured according to any appropriate method including a known method used in semiconductor manufacturing processes.
For example, the image sensor satisfying the conditions explained earlier is prepared, and the light shields 30 according to the present embodiment are formed on the image sensor 10 according to a known method used in semiconductor manufacturing processes. Moreover, the lens array 20 satisfying the conditions explained earlier can be separately manufactured according to a known method, and can be placed on top of the light shields 30.
Then, as may be necessary, the second-type light shields 40 and the cover glass 50 are placed above the lens array 20. In this way, the biological information obtaining device 1 according to the present embodiment can be manufactured.
<Regarding Biological Information Obtaining Method>
As explained above, using the biological information obtaining device 1 in which the light guiding paths are formed to have unequal opening diameters along the surface normal direction of the image sensor; biological information, which represents image information obtained as a result of emitting the light of a predetermined wavelength onto one part of the living body LB, is imaged in the image sensor 10 using the lens array 20, which has a plurality of single lenses 203 arranged in an array-like manner, via the light guiding paths formed due to the light shields 30. As a result, for example, it becomes possible to accurately obtain a variety of biological information such as image information related to fingerprints (for example, fingerprint pattern images indicating the distribution of the fingerprints); image information related to perspiration (for example, images indicating the presence or absence of perspiration); image information related to blood flow; image information related to pulse wave or pulsation; and image information related to blood vessels (for example, vein pattern images indicating the distribution of veins).
<Implementation Examples of Biological Information Obtaining Device 1>
The biological information obtaining device 1 according to the present embodiment can be implemented in any known type of device that performs biological authentication using biological information and provides various services according to the authentication result. In the biological information obtaining device 1 according to the present embodiment, since the occurrence of stray light is held down to a greater extent, it becomes possible to obtain biological information with a higher degree of accuracy. As a result of using the obtained biological information, authentication of individual users can be performed with a higher degree of accuracy.
For example, the biological information obtaining device 1 according to the present embodiment can be installed in a mobile device such as a smartphone SP illustrated in
In the case of installing the biological information obtaining device 1 according to the present embodiment in a wearable device, it is installed inside the device main body configured to be wearable by the user (for example, inside the main body of the smartwatch SW illustrated in
Although the application concerned is described above in detail in the form of a preferred embodiment with reference to the accompanying drawings; the technical scope of the application concerned is not limited to the embodiment described above. That is, the application concerned is to be construed as embodying all modifications such as other embodiments, additions, alternative constructions, and deletions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
Moreover, the effects described in the present written description are only explanatory and exemplary, and are not limited in scope. That is, in addition to or in place of the effects described above, the technology disclosed in the application concerned enables achieving other effects that may occur to one skilled in the art.
Meanwhile, a configuration as explained below also falls within the technical scope of the application concerned.
(1)
A biological information obtaining device comprising:
an image sensor in which biological information, which represents image information obtained as a result of emitting light of predetermined wavelength with respect to one part of a living body, is imaged;
a lens array that
a light shield that
the light guiding path is formed to have unequal opening diameter along surface normal direction of the image sensor.
(2)
The biological information obtaining device according to (1), wherein opening diameter of the light guiding path changes in a continuous manner along the surface normal direction.
(3)
The biological information obtaining device according to (1), wherein opening diameter of the light guiding path changes in a discontinuous manner along the surface normal direction.
(4)
The biological information obtaining device according to any one of (1) to (3), wherein, when the light shield is cut parallel to the surface normal direction, outside shape of the light shield facing the light guiding path is formed by at least either straight lines or curved lines.
(5)
The biological information obtaining device according to any one of (1) to (4), wherein the light shield is a laminated body in which two or more light shielding members having predetermined shape are laminated along the surface normal direction.
(6)
The biological information obtaining device according to any one of (1) to (5), wherein opening diameter of the light guiding path is equal to or greater than twice wavelength of light constituting the biological information.
(7)
The biological information obtaining device according to any one of (1) to (6), wherein opening diameter of the light guiding path is equal to or greater than 0.5 times and equal to or smaller than four times lens diameter of the single lenses.
(8)
The biological information obtaining device according to any one of (1) to (7), wherein, when A [mm] represents distance from sensor surface of the image sensor to the one part of the living body and when M represents lens magnification of the single lenses, length of the light guiding path is smaller than (A×M)/(1×M) [mm].
(9)
The biological information obtaining device according to any one of (1) to (8), wherein distance from sensor surface of the image sensor to the one part of the living body is equal to or greater than 0.5 mm and smaller than 30 mm.
(10)
The biological information obtaining device according to any one of (1) to (10), wherein
lens diameter of the single lenses is equal to or greater than 20 times pixel size of the image sensor,
lens magnification of the single lenses is smaller than one times, and
when s represents minimum value of photographic subject size to be resolved, when M represents lens magnification, and when N represents pixel size of the image sensor, relationship s×M>2×N is established.
(11)
The biological information obtaining device according to any one of (1) to (10), wherein
in between the lens array and the one part of the living body,
light source unit for emitting light of the predetermined wavelength onto the one part of the living body is disposed around the cover glass.
(12)
The biological information obtaining device according to any one of (1) to (11), wherein an absorber having light absorptivity of 90% or higher at a predetermined wavelength is disposed on surface of the light shield facing the light guiding path.
(13)
The biological information obtaining device according to any one of (1) to (12), wherein regular reflection prevention processing is performed on surface of the light shield facing the light guiding path.
(14)
The biological information obtaining device according to any one of (1) to (13), wherein material of the light shield is made of at least either metal, or resin compound, or dielectric substance.
(15)
The biological information obtaining device according to any one of (1) to (14), wherein the biological information indicates at least either image information related to fingerprints, or image information related to perspiration, or image information related to blood flow, or image information related to pulse wave or pulsation, or image information related to blood vessels.
(16)
The biological information obtaining device according to any one of (1) to (15), wherein the biological information indicates at least two types of image information selected from among image information related to fingerprints, image information related to perspiration, image information related to blood flow, image information related to pulse wave or pulsation, and image information related to blood vessels.
(17)
The biological information obtaining device according to any one of (1) to (16), wherein the biological information obtaining device is installed in a mobile device, a wearable device, or a stationary device, or is installed in an external device attachable to a stationary device.
(18)
A biological information obtaining method comprising performing imaging of biological information, which represents image information obtained as a result of emitting light of predetermined wavelength with respect to one part of a living body, using a lens array, which has a plurality of single lenses arranged in an array-like manner, in an image sensor via a light guiding path formed by a light shield, wherein
the light guiding path is formed to have unequal opening diameter along surface normal direction of the image sensor.
(19)
A wearable device comprising:
a device main body that is wearable by user; and
a biological information obtaining device that is installed in the device main body, wherein
the biological information obtaining device includes
the light guiding path is formed to have unequal opening diameter along surface normal direction of the image sensor.
Number | Date | Country | Kind |
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2018-004015 | Jan 2018 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2018/038583 | 10/17/2018 | WO | 00 |