JP2009043138A - Biological information acquisition device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a conventional biological information acquisition device is not designed with consideration of pattern variation of a thin blood vessel, for example, in order to assure the reliability of biometrics authentication, it is necessary to apply complicated imaging processing etc. to biometrics authentication equipment. <P>SOLUTION: The biological information acquisition device D1 is equipped with: an imaging device 31 which has a plurality of pixels PX; a transparent substrate 50 which has a plurality of microlenses 52 prepared corresponding to the plurality of pixels PX; and an optical channel separating layer 32 which is formed so that each of optical channels between a microlens 52 and a pixel PX is separated and has a light shielding structure in which an aperture corresponding to the pixel PX is prepared. The microlens 52 condenses light from a predetermined portion 100 through the aperture to the pixel PX. The minimum lens width of the microlens 52 is 50 μm or more. And distance between adjacent microlenses 52, and distance between apertures corresponding to the distance is nearly equal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a biological information acquisition apparatus that images a vein pattern in a predetermined portion based on reflected light or transmitted light from a predetermined portion of a subject.

  In recent years, the development of technology related to biometric authentication has been remarkable. As is well known, biometric authentication is a technique for identifying an individual from other individuals based on a determination whether biometric information acquired from an individual to be examined is equal to biometric information set in advance. . For example, there are a method for identifying an individual based on the iris of a human pupil, a method for identifying an individual based on a vein pattern such as a human finger, and a method for identifying an individual based on a fingerprint pattern of a finger. Among them, those using vein patterns such as human fingers are difficult to disguise pattern data, and high security can be ensured.

Patent Document 1 discloses an imaging device used for biometric authentication. In this imaging apparatus, the imaging apparatus is downsized by stacking the light source (100), the support base (300), and the image authentication unit (200).
JP 2001-119008 A

  In general, when biometric authentication is realized based on an image indicating biometric information, the acquired image of the image acquisition device is preferably higher in resolution. This is because an error rate of biometric authentication can be reduced by acquiring a high-resolution image and performing biometric authentication based on the high-resolution image. In order to improve the sensitivity characteristics of the image sensor, a general microlens (lens diameter of about 5 to 10 μm) is preferably arranged on each pixel.

  However, the above points cannot be immediately applied when biometric authentication is realized based on an image representing a vein pattern. This is because, when performing biometric authentication based on an image representing a vein pattern, it is extremely important to consider the vein pattern variation in a predetermined portion of the subject.

  A vein is a blood flow path that returns venous blood flowing out through capillaries to the heart. In particular, many capillaries diverge from veins at the end portions such as human fingers or hand portions. Capillaries expand / contract and generate / disappear due to seasonal influences and the influence of human health. Therefore, even if the predetermined portion of the subject to be observed is the same due to the variation in the pattern of thin blood vessels exemplified by capillaries (hereinafter sometimes simply referred to as pattern variation), it is set in advance. An acquisition pattern acquired each time may not match the master pattern. That is, the reliability of the biometric authentication device may be reduced due to the variation of the thin blood vessel pattern in a predetermined portion of the observation target.

  In order to ensure the reliability of biometric authentication, for example, in order to eliminate the influence of the above-described pattern variation, it is preferable to perform image processing in a subsequent signal processing unit. However, a pattern of thin blood vessels such as capillaries is selectively used. Therefore, it is necessary to perform relatively complicated image processing.

  In other words, the conventional biometric information acquisition device does not take into account the fluctuation of the thin blood vessel pattern, and it may be necessary to apply complex image processing or the like to the biometric authentication device in order to ensure the reliability of biometric authentication. Was.

  The present invention has been made to solve such problems, and relates to a biometric information acquisition apparatus used for a biometric authentication apparatus that performs biometric authentication based on an image representing a vein pattern. It is an object of the present invention to provide a biological information acquisition apparatus that can suppress a decrease in reliability.

  A biological information acquisition apparatus according to the present invention is a biological information acquisition apparatus that images a vein pattern in a predetermined portion based on reflected light or transmitted light from a predetermined portion of a subject, and an imaging element having a plurality of pixels A transparent substrate having a plurality of microlenses provided corresponding to the plurality of pixels, and an opening corresponding to the pixels formed to separate the optical channels between the microlenses and the pixels. An optical channel separation layer having a light shielding structure provided, and each of the plurality of microlenses condenses light from the predetermined portion to the pixel through the opening, and each of the minimum of the plurality of microlenses. The lens width is 50 μm or more, and the distance between the adjacent microlenses and the distance between the corresponding openings are substantially equal.

  By condensing light from a predetermined portion through each aperture of the image sensor through the opening through a microlens having a lens width of 50 μm or more, it is possible to prevent a thin blood vessel pattern from appearing clearly in the acquired vein pattern. . Thereby, the vein pattern indispensable for biometric authentication is relatively clarified. Further, the distance between the adjacent microlenses and the distance between the corresponding openings are substantially equal. Therefore, the images acquired in units of microlenses are suppressed from being superimposed on each other, and a clearer image can be acquired.

  The plurality of microlenses are preferably formed in a matrix on the main surface of the transparent substrate.

  It is preferable to further include a semiconductor light emitting element that emits light to be irradiated to the predetermined portion. By condensing light from a predetermined portion on each pixel of the image sensor through a microlens having a lens width of 50 μm or more, the amount of light input to each pixel corresponds to the lens width. Thereby, it becomes possible to set the emitted light intensity of the semiconductor light emitting element lower.

  A semiconductor light-emitting element that emits light to be irradiated to the predetermined portion; a first surface; and a second surface that faces the predetermined portion; the first surface to the second surface; And a light guide for guiding the emitted light. By condensing light from a predetermined portion on each pixel of the image sensor through a microlens having a lens width of 50 μm or more, the amount of light input to each pixel corresponds to the lens width. This makes it possible to set the intensity of light emitted from the semiconductor light emitting element to be lower.

  The optical channel separation layer may be laminated on the imaging device, and the transparent substrate may be laminated on the optical channel separation layer.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the reliability of biometric authentication by vein pattern fluctuation | variation can be suppressed with the structure itself of a biometric information acquisition apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each embodiment is simplified for convenience of explanation. Since the drawings are simple, the technical scope of the present invention should not be interpreted narrowly based on the drawings. The drawings are only for explaining the technical matters, and do not reflect the exact sizes or the like of the elements shown in the drawings. The same elements are denoted by the same reference numerals, and redundant description is omitted. Words indicating directions such as up, down, left, and right are used on the assumption that the drawing is viewed from the front.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic perspective view of the biological information acquisition apparatus D1. FIG. 2 is a schematic diagram for explaining the configuration of the biological information acquisition device D1 as viewed from above. FIG. 3 is a schematic explanatory view of the biological information acquisition device D1 as viewed from the point A in FIG. FIG. 4 is a schematic explanatory view of the biological information acquisition device D1 viewed from the point B side in FIG. In FIGS. 3 and 4, for convenience of explanation, a schematic cross-sectional view of the biological information acquisition device D <b> 1 from the point A or the point B is also shown. FIG. 5 is a schematic diagram for explaining an arrangement configuration of pixels of the photosensor 31. FIG. 6 is a schematic diagram for explaining the top view shape of the microlens. FIG. 7 is an explanatory diagram for explaining the function of the lens. FIG. 8 is an explanatory diagram for explaining an acquired image.

  As shown in FIG. 1, the biological information acquisition apparatus D1 includes a light irradiation device (light irradiation unit) LEa, a light irradiation device (light irradiation unit) LEb, a wiring board 30, a photosensor (imaging device) 31, and an optical channel separation layer. 32, a lens array 33 and a band pass filter 34.

  The light irradiation device LEa is disposed on the main surface 34 a of the bandpass filter 34. Similarly, the light irradiation device LEb is also disposed on the main surface 34a of the bandpass filter 34. The light irradiation device LEa and the light irradiation device LEb are arranged to face each other across the surface region R1. A human (subject) finger (target portion) is placed on the surface region R1. Each of the light irradiation devices LEa and LEb emits inspection light to be irradiated to a human finger.

  The light irradiation device LEa includes a light shielding plate (light shielding member) 2a, a light guide 3a, and a light emitting diode 4a (4a1, 4a2, 4a3, 4a4).

  The light shielding plate 2a is a plate-like member made of a material (metal, black resin, etc.) that blocks light from the light emitting diode 4a. A light guide 3a is fixed on the light shielding plate 2a. Note that an air layer may exist between the light shielding plate 2a and the light guide 3a in order for light to efficiently propagate through the light guide 3a. Light emitting diodes 4a1 to 4a4 are fixed to the light incident surface 3a2 of the light guide 3a.

  The light guide 3a is a plate-like member having a quadrilateral shape when viewed from above. The light guide 3a is a member that is substantially transparent to the inspection light emitted from the light emitting diode (transmittance is 90% or more, and here, the transmittance is 99%). For example, the light guide 3 is made of a resin material such as polycarbonate, acrylic, polyolefin, or a glass substrate.

As shown in FIG. 2, the light guide 3a has a light emitting surface (second side surface) 3a1 and a light incident surface (first side surface) 3a2. The light emission surface 3a1 is a side surface facing a finger placed on the surface region R1. The light incident surface 3a2 faces the light emitting surface 3a1. The light emitting surface 3a1 and the light incident surface 3a2 are long surfaces extending along the z axis with the z axis as the longitudinal direction. The light guide 3a includes a width _{W LG2} along the width _{W LG1} and z axis along the x-axis. The width W _LG1 is narrower than the width W _LG2 .

  The light emitting diodes 4a1 to 4a4 are arranged at substantially equal intervals. Thereby, the intensity distribution of the inspection light emitted from the light emitting surface 3a1 is made uniform to a practical level.

  As shown in FIG. 2, the inspection light emitted from the light emitting diode 4a1 is guided to the region R4a1 of the light emitting surface 3a1. The inspection light emitted from the light emitting diode 4a2 is guided to the region R4a2 of the light emitting surface 3a1. The inspection light emitted from the light emitting diode 4a3 is guided to the region R4a3 of the light emitting surface 3a1. The inspection light emitted from the light emitting diode 4a4 is guided to the region R4a4 of the light emitting surface 3a1.

  A region RO where the region R4a1 and the region R4a2 overlap is formed on the light emitting surface 3a1. A region RO where the region R4a2 and the region R4a3 overlap is formed on the light emitting surface 3a1. A region RO where the region R4a3 and the region R4a4 overlap is formed on the light emitting surface 3a1. That is, a region where inspection light from one light emitting diode and inspection light from another light emitting diode overlap is formed on the light emitting surface 3a1. By setting in this way, the inspection light can be emitted from almost the entire area of the light emission surface 3a1.

In the biological information acquisition device D1, biological information (an image representing a vein pattern) is acquired based on output signals from a plurality of pixels arranged two-dimensionally. Accordingly, it is preferable to irradiate the living body part to be observed with uniform inspection light over the entire area. If there is a part where the inspection light is not irradiated on the biological part to be observed, biometric information cannot be obtained from that part, and thus high-precision biometric authentication cannot be realized. In the present embodiment, in view of this point, the width W _LG1 of the light guide 3a is set so that the above-described region RO is formed on the light emitting surface 3a1.

  Also, Lambert distribution inspection light is emitted from the light emitting diodes 4a1 to 4a4. In the Lambert distribution, the light intensity at the center of the distribution is strong, and the light intensity at the bottom of the distribution is weak. Therefore, by superimposing the inspection lights emitted from the adjacent light emitting diodes, the intensity distribution of the inspection light emitted from the light emitting surface 3a1 can be made uniform. That is, by forming the above-described region RO on the light emitting surface 3a1, the intensity distribution of the inspection light emitted from the light emitting surface 3a1 can be made uniform along the longitudinal direction of the light emitting surface 3a1.

  The above description regarding the light irradiation device LEa applies to the light irradiation device LEb as it is. Here, overlapping description is omitted.

  As shown in FIG. 2, the light emitting diodes 4a1 to 4a4 are arranged on the light guide 3a in a state of being arranged along the longitudinal direction of the light incident surface 3a2. The light emitting diodes 4a1 to 4a4 are attached to the light incident surface 3a2 through the adhesive 11. In other words, the light emitting diodes 4a1 to 4a4 are optically coupled to the light incident surface 3a2 via the adhesive 11. The inspection light emitted from the light emitting diodes 4a1 to 4a4 passes through the light incident surface 3a2 of the light guide 3a and is introduced into the light guide 3a. The light guide 3a guides inspection light from the light incident surface 3a2 to the light emitting surface 3a1.

  The adhesive 11 has a high transmittance with respect to the inspection light and is substantially transparent with respect to the inspection light. Therefore, good optical coupling can be ensured between the light incident surface and the light emitting diode. Each of the light emitting diodes 4a1 to 4a4 is an element in which a monolithic semiconductor element is packaged. The light-emitting diodes 4a1 to 4a4 are semiconductor light-emitting elements that emit light in an orange to near-infrared region (light of either 580 nm or 1000 nm) when a current flows.

  The configuration of the light guide 3b of the light irradiation device LEb is substantially the same as the configuration of the light guide 3a of the light irradiation device LEa. That is, the light emitting surface 3b1 corresponds to the light emitting surface 3a1, and the light incident surface 3b2 corresponds to the light incident surface 3a2.

  In the light irradiation device LEa, the inspection light from the light emitting diode 4a1 propagates in the light guide 3a as follows. The inspection light emitted from the light emitting diode 4a1 passes through the adhesive 11, passes through the light incident surface 3a2 of the light guide 3a, propagates through the light guide 3a, and is emitted from the light emitting surface 3a1. The other light emitting diodes 4a2 to 4a4 are the same as in the case of the light emitting diode 4a1.

  FIG. 3 shows a schematic explanatory view of the biological information acquisition device D1 from the point A side in FIG. FIG. 4 shows a schematic explanatory view of the biological information acquisition device D1 from the point B side in FIG.

  As shown in FIG. 3, a photosensor (imaging device) 31, an optical channel separation layer 32, a lens array 33, a bandpass filter 34, and a light irradiation device LEa are arranged in this order on the upper surface of the wiring board 30. . A semiconductor integrated circuit 35 and a connector 36 are disposed on the lower surface of the wiring board 30.

  The light irradiation devices LEa and LEb are as described above.

  The band pass filter 34 is a plate-like optical member that selectively passes the wavelength of the inspection light (orange to near-infrared band (580 nm to 1000 nm, more preferably 600 nm to 860 nm)).

  The lens array 33 is disposed below the band pass filter 34. The lens array 33 includes a transparent substrate 50, a microlens (condensing lens) 52, and a spacer 51. On the upper surface of the transparent substrate 50, a spacer layer for supporting the plurality of microlenses 52 and the bandpass filter 34 arranged in a two-dimensional manner is arranged corresponding to each pixel PX of the photosensor 31. The transparent substrate 50 and the microlens 52 are made of a material that is substantially transparent to the inspection light. The transparent substrate 50 is a so-called glass substrate.

  The optical channel separation layer 32 is disposed below the lens array 33. The optical channel separation layer 32 includes a light shielding film 40, a first transparent layer 41, a second transparent layer 42, and a light shielding layer 43.

  The light shielding film 40 is a layer formed in a lattice shape on the lower surface of the lens array 33. The light shielding film 40 has a plurality of openings OP1 formed in a matrix corresponding to each microlens 52 of the lens array 33. Note that the plurality of openings OP1 means openings in an optical sense. Here, the opening OP <b> 1 is filled with the first transparent layer 41.

  The first transparent layer 41 is a layer made of resin, and is substantially transparent to inspection light.

  The second transparent layer 42 is a resin layer made of the same material as the first transparent layer 41. Therefore, the second transparent layer 42 is also substantially transparent to the inspection light. The second transparent layer 42 has a plurality of lands 42a. The land 42a is two-dimensionally arranged corresponding to each pixel PX of the photosensor 31. In addition, a land means the island-shaped part prescribed | regulated by a groove | channel. Each land need not be completely separated from each other.

  The light shielding layer 43 is formed so as to cover the land 42a. The light shielding layer 43 has an opening OP <b> 2 provided at a position corresponding to the condensing position of each microlens 52 of the lens array 33. The opening OP2 also corresponds to the arrangement position of each pixel PX of the photosensor 31. The opening OP2 is two-dimensionally arranged corresponding to each pixel PX of the photosensor 31.

  The photo sensor 31 is disposed below the optical channel separation layer 32. As shown in FIG. 5, the photo sensor 31 is an imaging device having a plurality of pixels arranged in a matrix. The photosensor 31 has an imaging region R2 in which a plurality of pixels PX are arranged two-dimensionally. Each pixel PX corresponds to the opening OP <b> 2 formed in the light shielding layer 43. Therefore, the light condensed by the microlens 52 is efficiently incident on the pixel PX. In the present embodiment, each pixel is configured by a TFT (Thin Film Transistor) as an optical transistor. The imaging region R2 is provided in a region corresponding to the surface region R1. The pixel PX is provided at a position corresponding to the focal position of the microlens 52.

  When the inspection light reflected in the finger enters the pixel PX of the photosensor 31, an electric charge corresponding to the intensity of the inspection light is generated in the pixel PX. Then, a signal corresponding to the generated charge is output from the photosensor 31, and an image is configured based on the output signal. Thereafter, based on the processing result in the subsequent arithmetic processing unit, it is determined whether the observed human is a specific human being set in advance.

  The wiring board 30 is a wiring board made of glass epoxy resin or the like, and elements are mounted on both upper and lower surfaces.

  Note that a drive circuit 37 that controls the reading operation of the photosensor 31 and the like is disposed on the upper surface of the photosensor 31. A signal acquired by the photosensor 31 is transmitted to the semiconductor integrated circuit 35 through the wire 38, the through electrode 39 that connects the upper surface and the lower surface of the wiring substrate 30, and the wiring formed on the lower surface of the wiring substrate 30. . The connector 36 constitutes an interface part related to the connection between the biological information acquisition device D1 and an external signal processing circuit.

  The semiconductor integrated circuit 35 is a so-called ASIC (Application Specific Integrated Circuit). In the semiconductor integrated circuit 35, predetermined information processing (for example, determination of consistency between acquired image information and pre-stored image information (master data)) is executed. The information processing result in the semiconductor integrated circuit 35 is communicated to another information processing unit (not shown).

  Further, as shown in FIG. 3, the thickness from the light irradiation devices LEa and LEb to the bandpass filter 34 is preferably 1.7 mm or less. The thickness from the lens array 33 to the photosensor 31 is preferably 1.0 mm or less. If it does in this way, the thickness from light irradiation device LEa, LEb to the photosensor 31 can be 3 mm or less. Therefore, a very thin biometric information acquisition apparatus can be realized.

  In addition, as shown in FIG. 3, the width | variety along the x-axis of surface region R1 was 25 mm. Moreover, as shown in FIG. 4, the width along the z-axis of the surface region R1 was 15 mm. As schematically shown in FIGS. 3 and 4, a finger is placed on the surface region R <b> 1 to obtain biological information. At this time, the surface region R1 is covered with a finger. Therefore, disturbance light incident on the surface region R1 is suppressed.

  Next, functions of the biological information acquisition device D1 will be described. As schematically shown in FIG. 3, the inspection light reflected by the internal region RP of the finger 100 is incident on the pixel PX of the photosensor 31 through the microlens 52 of the lens array 33. In the following, description will be given in order. The internal region RP is a region having a depth of about 1 mm from the lower surface of the finger 100.

  The inspection light emitted from the light emission surfaces of the light irradiation devices LEa and LEb is applied to the human finger 100. Inside the human finger 100, the inspection light is reflected by an internal scatterer. Further, the inspection light is absorbed by the vein of the human finger 100. The inspection light reflected by the human finger 100 enters the surface region R1.

  The inspection light incident on the surface region R1 passes through the band pass filter 34. The disturbance light other than the inspection light is blocked by the band pass filter 34. Since the noise component can be blocked by the band pass filter 34, a higher quality image can be acquired.

  The inspection light that has passed through the band pass filter 34 enters the lens array 33. In the lens array 33, the light is condensed on each pixel PX of the photosensor 31 by each microlens 52 disposed on the upper surface of the transparent substrate 50.

  The light condensed by the microlens 52 of the lens array 33 is incident on the optical channel separation layer 32. As described above, the optical channel separation layer 32 has the opening OP1 and the opening OP2 that are two-dimensionally arranged corresponding to each pixel of the photosensor 31. The photosensor 31 has lands 42 a that are two-dimensionally arranged corresponding to the pixels. A light shielding layer 43 is filled between adjacent lands 42a. A light shielding layer 43 is also formed on the lower surface of the land 42a. In the present embodiment, the light shielding layer 43 is made of a material that absorbs light in the orange to near infrared region. The stray light incident on the light shielding layer 43 is effectively absorbed by the material constituting the light shielding layer 43.

  With such a light shielding structure, the optical channel separation layer 32 separates optical paths (optical channels) from the microlens 52 of the lens array 33 to the pixel PX of the photosensor 31. Then, crosstalk (interference) that can occur between optical channels is suppressed. Since the inspection light is condensed as it proceeds from the microlens 52 to the pixel PX, the opening width of the opening OP2 is set to be narrower than the opening width of the opening OP1.

  Light incident on each pixel of the photosensor 31 is photoelectrically converted by each pixel. Then, it is read out as an electrical signal and processed by the semiconductor integrated circuit 35 described above. Based on the inspection light from the living body, an image in which the vein pattern of the finger 100 appears can be acquired.

  Here, FIG. 6 shows a schematic view of the microlens 52 and the like partially viewed from above. FIG. 7 is an explanatory diagram for explaining the function of the microlens 52. FIG. 8 is an explanatory diagram for explaining the acquired image.

  As shown in FIG. 6, the top view shape of the microlens 52 is circular. The microlens 52 is a spherical lens, and its lens width w is 50 μm or more. As a result, the thin blood vessel pattern is suppressed from appearing clearly in the acquired image, as will be described later, and the vein pattern indispensable for biometric authentication can be relatively clarified. Note that the lens width w matches the width of the microlens 52 in a top view, and here, the lens width w matches the lens diameter of the microlens 52.

  The lens width w of the micro lens 52 is preferably 50 μm or more and 300 μm or less. By setting it to 300 μm or less, a necessary resolution can be ensured, and an image representing a vein pattern can be acquired appropriately.

  The lens width w may be 70 μm or more. In this case, the same effect as described above can be obtained. The lens width w may be 200 μm or less. In this case, the same effect as described above can be obtained.

  That is, the lens width w of the microlens 52 is preferably 50 μm or more and 300 μm or less. More preferably, the lens width w of the micro lens 52 is 70 μm or more and 200 μm or less.

  As schematically shown in FIG. 7, the microlens 52 is arranged corresponding to each pixel PX. The micro lens 52a condenses light on the pixel PXa in a range of a region R1 corresponding to the top view shape. The microlens 52b collects light on the pixel PXb in a range of a region R2 corresponding to the top view shape. The micro lens 52c condenses light on the pixel PXc in a region R3 corresponding to the top view shape. In other words, the microlens 52 collects at least light in a range corresponding to the top view shape on each pixel. In this case, the light input to each pixel is averaged according to at least the top view shape of the microlens 52.

  As described above, each of the microlenses 52 according to the present embodiment collects light from the outside in a range (region R1, region R2, region R3) corresponding to the top view shape. This is because the microlens 52 has a depth of field corresponding to a shallow distance of about 1 to 5 mm from the skin. Further, as schematically shown in FIG. 7, the distance P1 between the adjacent microlenses 52 and the distance P2 between the corresponding openings are substantially equal. In other words, the arrangement interval of the microlenses 52 and the arrangement interval of the openings are substantially the same. Thereby, for example, the image from the region R1 and the image from the region R2 are suppressed from being superimposed, and the image acquired by the photosensor 31 can be suppressed from becoming unclear. The opening is determined according to the configuration of the optical channel separation layer 32, and corresponds to the above-described opening OP1, opening OP2, or land 42a here.

  Although the inspection light is absorbed in a portion where there is a capillary blood vessel or the like, the inspection light is reflected or transmitted through the living tissue around the capillary blood vessel. Therefore, if the top view shape of the microlens is set to a minimum lens width of 50 μm or more, the absorption of light in capillaries or the like of 50 μm or less with the reflected light or transmitted light from the surrounding living tissue is averaged with the surroundings. No longer identified.

  And as shown to Fig.8 (a) (b), the image itself acquired with a biometric information acquisition apparatus can be corrected. That is, the thin blood vessel 201 branched from the vein 200 as shown in FIG. 8A can be erased as shown in FIG. The vein pattern essential for biometric authentication is relatively clarified. That is, the configuration of the biometric information acquisition apparatus itself can suppress a decrease in biometric authentication reliability due to vein pattern fluctuations.

  Note that FIG. 8 is created for convenience of explanation, and it is not always necessary to confirm a desired effect in such a degree and manner. In practice, the vein pattern is acquired as black (dark part).

  Further, the intensity of light input to each pixel depends on the lens width. In this embodiment, the microlens 52 is set to have a lens width of 50 μm or more as described above. Since the microlens 52 collects at least light in a range corresponding to the top view shape of the microlens 52 on the pixel, even if the intensity of light emitted from the light irradiation devices LEa and LEb is set to a lower value, The intensity of light input to each pixel can be set to a value necessary for pattern acquisition. Accordingly, it is possible to reduce the power consumption of the biological information acquisition device D1. The reduction of power consumption is particularly advantageous when the biological information acquisition device D1 is mounted on a small mobile information device such as a mobile phone.

  In addition, light collected by the microlens 52 is input to each pixel, and in the present embodiment, the microlens 52 is set to have a lens width of 50 μm or more as described above. Since the microlens 52 condenses at least light in a range corresponding to the top view shape of the microlens 52 on the pixel, even if there is partial unevenness in the intensity distribution of the light irradiated to the finger, It is possible to suppress partial unevenness in the acquired image due to the influence. The characteristics of semiconductor light emitting devices such as the light emitting diodes 4a and 4b may vary due to the influence of manufacturing conditions, usage environment, changes with time, and the like. If the lens width of the microlens 52 is set to 50 μm or more as in the present embodiment, it is possible to reduce the influence of partial unevenness in the intensity distribution of light irradiated to the finger.

  In the present embodiment, the microlens 52 is disposed corresponding to each pixel PX. Further, the microlens 52 collects light in a range corresponding to at least the top view shape on each pixel. As a result, the light input to each pixel is averaged at least within the range of the top view shape of the microlens 52. In particular, by making the lens width of the microlens 52 have a relatively large aperture of 50 μm or more, the above-described effects are effectively realized.

  The depth of field of the microlens 52 corresponds to the depth from the epidermis of the vein by setting the lens diameter of the microlens 52 within a range of 50 μm to 300 μm (more preferably, 70 μm to 200 μm). It can also be set.

  The depth from the epidermis is quantitatively about 1 to 5 mm. FIG. 9 shows the relationship between the lens diameter, depth of field, and MTF (Modulation Transfer Function) according to this embodiment. MTF is an index indicating resolution. The larger the MTF value, the higher the resolution, but it can be set appropriately according to the purpose such as the authentication level and the security level. Since MTF 40% or more can meet various requirements, it is desirable that MTF 40% or more. Although the lens diameter of the microlens according to the present embodiment is 50 μm or more (more preferably 70 μm or more), it can be seen that it has a depth of field showing a high MTF at a position corresponding to the depth from the epidermis of the vein.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIG. FIG. 10 is a schematic explanatory diagram for explaining a top view shape of the microlens. The difference from the first embodiment is only the top view shape of the microlens.

  As shown in FIG. 10, in the present embodiment, the top view shape of the microlens 52 is a quadrangular shape. The micro lens 52 has a width W1 and a width W2. The width W2 is a larger value than the width W1. Here, the width W1 is set to 50 μm or more. That is, although the lens width has a predetermined range according to the shape of the microlens 52, the minimum lens width of the microlens 52 is preferably set to 50 μm or more. By doing in this way, the effect similar to the effect demonstrated in 1st Embodiment can be acquired.

[Third Embodiment]
A second embodiment of the present invention will be described with reference to FIG. FIG. 11 is a schematic explanatory diagram for explaining a top view shape of the microlens. The difference from the first embodiment is only the top view shape of the microlens.

  As shown in FIG. 11, in the present embodiment, the top view shape of the microlens 52 is a hexagonal shape. The microlens 52 has a width W1, a width W2, and a width W3. The relationship among the width W1, the width W2, and the width W3 is W2> W3> W1. Here, the width W1 is set to 50 μm or more. That is, although the lens width has a predetermined range according to the shape of the microlens 52, the minimum lens width of the microlens 52 is preferably set to 50 μm or more. By doing in this way, the effect similar to the effect demonstrated in 1st Embodiment can be acquired.

  The technical scope of the present invention is not limited to the above-described embodiment. The microlens 52 may have another shape when viewed from above. The specific configuration of the optical channel separation layer is arbitrary. The transparent substrate and the microlens may be integrally molded, or the microlens may be pasted on the transparent substrate. The transparent substrate is not limited to a single layer and may be a multilayer. The specific structure of the light irradiation device is arbitrary. A light reflecting surface may be added to the light guide, and light from the light incident surface to the light emitting surface may be guided through the light reflecting surface. A specific method for determining whether the acquired pattern matches the master pattern is arbitrary.

It is a schematic perspective view of biological information acquisition device D1. It is a schematic diagram for demonstrating the structure which looked at biometric information acquisition apparatus D1 from the top. It is the schematic explanatory drawing which looked at the biometric information acquisition device D1 from the A point side of FIG. It is the schematic explanatory drawing which looked at the biometric information acquisition device D1 from the B point side of FIG. 3 is a schematic diagram for explaining an arrangement configuration of pixels of a photosensor 31. FIG. It is a schematic diagram for demonstrating the top view shape of a micro lens. It is explanatory drawing for demonstrating the function of a lens. It is explanatory drawing for demonstrating the image acquired. It is a graph for demonstrating the characteristic of a micro lens. It is a schematic explanatory drawing for demonstrating the top view shape of a micro lens. It is a schematic explanatory drawing for demonstrating the top view shape of a micro lens.

Explanation of symbols

D1 Biological information acquisition apparatus LEa Light irradiation device LEb Light irradiation device 3a, 3b Light guide 4a, 4b Light emitting diode 11 Adhesive 30 Wiring board 31 Photo sensor 32 Optical channel separation layer 33 Lens array 34 Band pass filter 35 Semiconductor integrated circuit 36 Connector 40 light shielding film 41 transparent layer 42a land 42 transparent layer 43 light shielding layer 50 transparent substrate 51 spacer 52 microlens

Claims (5)

A biological information acquisition apparatus that images a vein pattern in a predetermined portion based on reflected light or transmitted light from a predetermined portion of a subject,
An imaging device having a plurality of pixels;
A transparent substrate having a plurality of microlenses provided corresponding to the plurality of pixels;
An optical channel separation layer having a light shielding structure formed so as to separate the optical channels between the microlens and the pixel and provided with an opening corresponding to the pixel;
With
Each of the plurality of microlenses condenses light from the predetermined portion on the pixel through the opening,
The minimum lens width of each of the plurality of microlenses is 50 μm or more,
A biological information acquisition apparatus, wherein a distance between adjacent microlenses is substantially equal to a distance between corresponding openings.   The biological information acquiring apparatus according to claim 1, wherein the plurality of microlenses are formed in a matrix on the main surface of the transparent substrate.   The biological information acquisition apparatus according to claim 1, further comprising a semiconductor light emitting element that emits light to be irradiated to the predetermined portion. A semiconductor light emitting element that emits light to be irradiated to the predetermined portion;
A light guide having a first surface and a second surface facing the predetermined portion, and guiding light emitted from the semiconductor light emitting element from the first surface to the second surface;
The biological information acquisition apparatus according to claim 1, further comprising: The optical channel separation layer is stacked on the image sensor,
The biological information acquisition apparatus according to claim 1, wherein the transparent substrate is stacked on the optical channel separation layer.

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