JP2010182328A - Device for imaging fingerprint image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for imaging fingerprint images, by which a stable fingerprint image having improved contrast is obtained. <P>SOLUTION: The device for imaging fingerprint images includes a light source 3 which takes a fingertip 1, having a fingerprint 11 to be picked up, as a specimen and irradiates the specimen with a light 30 which can be transmitted through the specimen; a specimen-holding section 2 capable of holding the specimen, in a state of non-contacting a surface of the fingerprint 11; an imaging means 5 for imaging the light 30 from the light source 3 which is transmitted through the specimen, to obtain a fingerprint image, wherein protruding portions of internal texture near the surface of the fingerprint 11 are dark and concave portions are the light 30 from the source 3; and an optical system 4 forming an image of the light 30 from the light source 3, which is transmitted through the specimen, on the imaging means 5. The optical system 4 is constituted, such that a plurality of regions of the fingerprint 11 are irradiated and is disposed such that a front end side of the fingertip 1 of the specimen is inclined at a prescribed angle to a plane orthogonal to an optical axis 400 of the optical system 4 so as to be farther away from the optical system 4 than the opposite side, in a state with a position where the belly side of the fingertip 1 is brought into contact with the specimen-holding section 2, as the criterion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fingerprint image capturing apparatus, and in particular, a fingerprint capable of obtaining a stable fingerprint image even when the fingerprint unevenness is unclear regardless of the moisture state of the fingerprint skin surface. The present invention relates to an image pickup apparatus.

  In a conventional fingerprint image pickup apparatus, a finger is held in a non-contact state with a fingerprint portion of a fingertip portion, light is irradiated from the back side (back side) of the fingertip portion, and light transmitted through the inside of the finger is detected. Since the transmittance of light transmitted through the fingertip portion is higher in the concave portion than in the convex portion of the fingerprint, an image in which the concave portion is brighter than the convex portion of the fingerprint is obtained (for example, see Patent Document 1).

JP 2003-85538 A (page 3-4, FIG. 1-4)

  The conventional fingerprint image pickup apparatus is configured as described above, and can obtain a stable fingerprint image even when the fingerprint unevenness is unclear, regardless of the moisture state of the fingerprint skin surface. Although it is possible, further improvement in the contrast of the fingerprint image is desired. In addition, there is a problem that a stable fingerprint image cannot be obtained if the installation position of the fingertip portion is shifted.

  An object of the present invention is to provide a fingerprint image imaging apparatus capable of stably obtaining a fingerprint image with improved contrast.

  The fingerprint image capturing apparatus according to the present invention uses a fingertip portion having a fingerprint to be imaged as an object, a light source that irradiates the object with light that can pass through the object, and a surface of the fingerprint in a non-contact state. An object holding unit that can hold the object, and an imaging unit that captures light from the light source that passes through the object and obtains a fingerprint image in which the convex part of the internal tissue near the surface of the fingerprint is dark and the concave part is bright And an optical system that causes the imaging means to form an image of light from the light source that passes through the subject, and the light from the light source irradiates a plurality of regions of the fingertip portion, and the optical system. The tip side of the fingertip part of the subject is farther from the optical system than the opposite side with reference to the position where the abdomen of the fingertip part is brought into contact with the subject holding part on a surface orthogonal to the optical axis of the subject. So that the optical system is tilted at a predetermined angle. It is obtained by location.

According to the fingerprint imaging apparatus according to the present invention, a fingertip portion having a fingerprint to be imaged is a subject, a light source that irradiates the subject with light that can pass through the subject, and the surface of the fingerprint is non-contact. An image of light from the light source that passes through the subject and the subject holding portion that can hold the subject in a state to obtain a fingerprint image in which the convex portion of the internal tissue near the surface of the fingerprint is dark and the concave portion is bright Therefore, a stable fingerprint image can be obtained regardless of the state of moisture on the skin surface of the fingerprint, even when the irregularities of the fingerprint are unclear.
In addition, the optical system includes an optical system that forms an image on the imaging unit with light from the light source that passes through the subject, and the light from the light source irradiates a plurality of regions of the fingertip portion. With reference to the position where the ventral side of the fingertip part is in contact with the subject holding part on a surface orthogonal to the optical axis, the tip side of the fingertip part of the subject is separated from the optical system compared to the opposite side. Since the optical system is arranged so as to be inclined at a predetermined angle, a fingerprint image with improved contrast can be stably obtained.
Therefore, more accurate fingerprint information can be obtained.

Embodiment 1 FIG.
The inventors of the present invention use a fingertip portion having a fingerprint to be imaged as a subject, irradiate the subject with light from a light source that can pass through the subject, and transmit the subject through an optical system. The light from the light source is imaged on an imaging means, and the light from the light source that passes through the subject is imaged by the imaging means to obtain a fingerprint image in which the convex portions of the fingerprint are dark and the concave portions are bright. In the previous application (Japanese Patent Application No. 2004-290575), the toe side is saturated and the root side becomes dark in the previous application (Japanese Patent Application No. 2004-290575). It has been disclosed that shading of the entire fingerprint image becomes gentle when irradiating a portion other than a substantially nail near the nail line, and the base side becomes brighter and the toe side becomes darker when irradiated near the first joint.
The inventors used the bone as the second light source, and the light hitting the bone was scattered at a wide angle and transmitted through the fingertip part to the fingerprint part with relatively uniform intensity. Because it is not, I guess that if the light from the light source is mainly applied to the nail, the light that did not hit the bone will be transmitted as it is and the shading will be tightened.
As a result, it is possible to capture a fingerprint image with reduced shading by irradiating light to a portion other than the substantially nail near the nail line, and a range including fingerprint information necessary for personal identification, which is a main part I thought that it would be possible to contribute to the optimization of lightness.

  The first embodiment is configured such that light from a light source irradiates a plurality of regions of a fingertip portion with respect to a fingerprint image capturing apparatus configured with attention to the above characteristics.

  In the present invention, the range including fingerprint information necessary for personal identification is, for example, the region from the first joint of the finger to the fingertip, the region including the first joint portion, or the fingerprint on the side of the finger. Refers to the included area.

  1 to 3 are diagrams for explaining a fingerprint image imaging apparatus according to Embodiment 1 of the present invention. More specifically, FIG. 1 is a side view showing the overall configuration of the fingerprint image imaging apparatus, and FIG. FIG. 6 is a bottom view showing a state in which the vicinity of the fingertip portion is viewed from the imaging means side (abdominal side). FIG. 3 is a top view showing the vicinity of the fingertip portion as viewed from the back side (nail side).

In the fingerprint image capturing apparatus according to the present embodiment, the fingertip portion 1 having the fingerprint 11 to be imaged is the subject, and the light 30 that can pass through the subject 1 is present in the presence of the nail 12 whose irradiation center is the fingertip portion 1. A light source 3 for irradiating a portion other than the substantially claw 12 with a plurality of irradiation spots, on the substantially center line in the width direction on the surface that is on the opposite side of the claw 12 with respect to the line of the claw 12;
Imaging means 5 for imaging the light 30 from the light source 3 that passes through the subject 1 to obtain a fingerprint image corresponding to the fingerprint 11 in which the convex portion of the fingerprint 11 is dark and the concave portion is bright;
An optical system 4 for imaging the light from the light source 3 that passes through the subject 1 on the imaging means 5;
A fingerprint image output from the imaging means 5 is subjected to image processing to obtain fingerprint information, and a signal processing unit 6 for identifying an individual based on the fingerprint information is provided.
Furthermore, means for adjusting the brightness of the image by adjusting at least one of the light irradiation conditions (luminance and irradiation region 16) and the gain of the image pickup means 5 (image pickup element 52) (lightness determination unit 66, light source drive circuit 32, Gain adjustment circuit 55),
Means (image processing unit 62) for superimposing or partially pasting a plurality of fingerprint images of different brightness on the same subject.

  In the present embodiment, a subject holding portion that can hold the fingertip portion 1 (in FIG. 1, a subject holding portion with an opening that can hold the fingertip portion 1 in a state where the surface of the fingerprint 11 to be imaged is not in contact with the fingertip portion 1 is provided. 2) is provided. The opening portion of the subject holding unit 2 with the opening is provided so as to include an observation surface 100 that is a range imaged by the imaging means 5.

  The fingertip portion 1 that is a subject has a fingerprint 11 to be imaged on the ventral side, and the fingerprint 1 has a concavo-convex pattern composed of a convex portion (mountain portion) and a concave portion (valley portion). In the present invention, the fingertip portion 1 refers not only to the tip portion of the finger, but also from the tip portion of the finger to the vicinity of the first joint or the second joint.

The light source 3 that irradiates the fingertip part 1 with light 30 that can be transmitted through the fingertip part 1 causes the light to travel from the dorsal side (nail side) opposite to the fingerprint 11 of the fingertip part 1 to the ventral side (fingerprint side). Is provided. As the light source 3, light having a main wavelength in the red light to near infrared light region, that is, projection light of any wavelength (monochromatic) in the red light to near infrared light region, or red light to near infrared light. Projection light in which light over a region is mixed, or light that emits light in the red wavelength to near infrared light region (monochromatic or mixed in some cases) as a main wavelength is used. For example, a laser, a light emitting diode, or a lamp light source is used. Light in the red light to near-infrared light region is preferably used because of its high light transmittance with respect to the living body that is the subject 1, but more preferably has a main wavelength in the range of 600 nm to 1400 nm. Furthermore, since the light absorption characteristic of hemoglobin in the blood vessel is minimum at around 660 nm, in order to reduce the influence of the blood vessel on the fingerprint image, light in a region where the main wavelength is 630 nm to 780 nm is more preferable.
Further, the fingertip portion 1 and the light source 3 may be covered with a light shield so as not to be affected by light from the outside.

The light source 3 is composed of one or more lasers, light emitting diodes, and lamp light sources, for example, and can be turned on at an arbitrary number simultaneously. When the fingertip portion 1 is held by the subject holding portion 2 with an opening and the observation surface 100 is at a position that fits within the opening of the subject holding portion 2 with an opening, for example, a predetermined region 16 of the fingertip portion as shown in FIG. It arranges so that can be irradiated. In addition, the light source driving circuit 32 is configured to control the irradiation condition (luminance and irradiation region 16) of the light 30 irradiated to the subject 1 by controlling the element to be turned on. For example, when the light source 3 is composed of a plurality of light emitting elements, each element or a small group of elements configured to irradiate the same position (area) irradiates different positions (areas) of the fingertip 1. Install as described. Furthermore, the irradiation region 16 in the subject 1 is configured to be a plurality of regions, for example, by controlling an element to be turned on according to a position (region) to be irradiated. Controlling the irradiation region 16 means controlling the position, the size of the region, and the number of regions individually or in combination. When controlling the number of regions, a plurality of light sources 3 may be provided.
When the light source 3 is composed of a plurality of light emitting elements, the light may be condensed using a lens or the like in order to determine the size of the region.
By irradiating the fingertip portion with a plurality of irradiation spots, the illuminance can be increased and the likelihood for the installation position of the fingertip portion can be increased.

In addition, the fingerprint image capturing apparatus according to the present embodiment includes a marker light source 33 that irradiates the marker light 31 near the position where the light from the light source 3 irradiates the subject 1.
In the marker light source 33, when the fingertip portion 1, which is a subject, is placed on the subject holding portion 2 with an opening and covers the opening, the marker light 31 does not enter the imaging element 52, and the subject light holding portion 2 with the opening is exposed. It is installed so that the marker light 31 is incident on the image sensor 52 in a state where the fingertip portion 1 is not placed.
Further, when the subject 1 is moved so that the marker light 31 is irradiated to the irradiation region 16 of the subject (fingertip portion) 1, the light from the light source 3 is irradiated to the irradiation region 16 of the subject 1. A subject 1 can be placed.
The marker light source 33 may be shared with the light source 3, but the marker light 31 has a meaning that, for example, a curve along an arrow or a nail skin, or other positions that can be read by humans and helped to understand the position where the finger is held up. A certain pattern may be projected from one light source to one or several places.
Further, the wavelength of the marker light 31 is not limited to the red light to the near infrared light region, but may be visible light that can be visually observed by the user.
In addition, since the marker light 31 does not enter the image sensor 52 when the fingertip portion 1 covers the opening, it is not only for positioning the subject but also for the presence of a finger that determines whether or not the subject exists at the light irradiation position. It can also be used for determination.
Further, another means is used for positioning the subject, and the marker light 31 can be used only for the finger presence determination. In this case, it is not necessary to be visible light.

The optical system 4 forms an image on the image sensor 52 with light from the light source 3 that passes through the convex portion of the fingerprint 11 on the fingertip 1 and light from the light source 3 that passes through the concave portion of the fingerprint 11. In the present embodiment, the optical system 4 is telecentric on the object side (subject 1 side) through which the transmitted light from the fingertip unit 1 first passes through the lens 41 and the transmitted light passes next to the lens 41. A diaphragm 42 is provided at such a position.
In order to obtain a clearer fingerprint image, the lens 41 is mainly provided with a telecentric effect, and a lens that mainly contributes to image formation is installed at a position where light passes after passing through the aperture 42. An optical system composed of a plurality of lenses may be configured by installing a lens having an effect of taking image distortion.

  The ventral side of the fingertip part 1, that is, the surface of the fingerprint 11 to be imaged is a curved surface, and the distance between the fingerprint 11 and the image sensor 52 varies depending on the location in the observation surface 100. Image distortion due to differences may occur. Therefore, by increasing the depth of field so that the entire surface of the observation surface 100 is in focus and adopting a telecentric optical system on the object side, the contrast is further improved without being affected by defocus or magnification fluctuation. Fingerprint image can be obtained.

  In the imaging means 5 (hereinafter also referred to as the imaging system 5), a fingerprint corresponding to a fingerprint is obtained by capturing an image in which light having an intensity distribution transmitted through the internal tissue of the fingertip portion 1 is imaged by the optical system 4. Get an image. The imaging unit 5 includes a wavelength selection element 51 as a wavelength selection unit, an imaging element 52, and an image output circuit 53 that converts an electrical signal from the imaging element 52 into an electrical image signal.

The wavelength selection element 51 (wavelength selection means) selectively transmits only light having the same wavelength as that of the light source 3 (red light to light in the near-infrared light region). For example, an interference filter, filter glass, or plastic filter is used. The output optical signal from the wavelength selection element 51 is imaged by the imaging element 52.
In FIG. 1, the wavelength selection unit 51 is provided between the diaphragm 42 and the image sensor 52. The wavelength selection unit 51 includes a plurality of lenses 41 between the lens 41 and the fingertip unit 1. It may be provided at any position such as between the lens and the lens 41 and the stop 42 when the lens is used. Moreover, the lens 41 and the image pick-up element 52 which have a wavelength selection function can also be used.

  The imaging element 52 is, for example, a two-dimensional solid-state imaging element such as a CCD (charge imaging element) or a CMOS (complementary metal oxide semiconductor) image sensor, an imaging tube, or the like. The image sensor 52 is sensitive to light passing through the fingertip part 1 and transmitted through the internal tissue of the fingertip part 1, that is, having sensitivity to light in the red light to near infrared light region. The imaging means 5 is shielded from receiving light other than light from the fingertip portion 1. In addition, a gain adjustment circuit 55 that adjusts the gain of the image sensor 52 is provided.

The signal processing unit 6 includes an image capturing unit 61 that receives a signal from the image output circuit 53, an image processing unit 62 that processes the signal from the image capturing unit 61 and performs binarization and thinning, and the image processing unit 62. A fingerprint data storage unit 63 that receives a signal from the image data and stores it as a registered image, and a personal identification unit 64 that performs personal identification by comparing the image from the image processing unit 62 with the image from the fingerprint data storage unit 63. The fingerprint image output from the image output circuit 53 is subjected to image processing to obtain fingerprint information, and an individual is identified based on the fingerprint information.
Furthermore, the signal processing unit 6 processes the signal from the image capturing unit 61, determines whether the signal is within a predetermined threshold range, determines whether the finger is present, and the light source driving circuit A finger presence determination unit 65 that can send a signal to 32 is provided.
The image capture unit 61 has a function of temporarily storing the captured fingerprint image.

Furthermore, the signal processing unit 6 determines whether the brightness of the fingerprint image captured by the image capturing unit 61 is within a predetermined threshold range, and based on the determination result, the light source driving circuit 32 and the gain adjustment circuit. And a lightness determination unit 66 that adjusts at least one of the irradiation condition (intensity, irradiation region 16) of the light 30 from the light source 3 that irradiates the fingertip unit 1 and the gain of the image sensor 52. ing. That is, the brightness determination unit 66 determines the image brightness of the entire image of the fingerprint image, the entire range where fingerprint information necessary for personal identification can be obtained, a region where a part of the region is extracted, or a divided region. Can be determined.
In addition, in the case where a plurality of images are captured for the same subject with at least one of the irradiation condition and the gain of the imaging means, the brightness determination circuit 66 may determine the brightness of the image every time imaging is performed. For example, the brightness of a plurality of areas is determined by a single determination and the result is stored. After that, the brightness of the image is calculated from the stored result without performing the brightness determination again so that each determined area is appropriate. It can also be adjusted.

  Further, in addition to the above-described processing such as binarization and thinning, the image processing unit 62 performs imaging by changing at least one of the irradiation condition of the light 30 to the subject 1 and the gain of the imaging means (imaging element 52). It also has a function of superimposing or partially pasting a plurality of fingerprint images.

  Note that it is not necessary that all of the parts provided in the signal processing unit 6 are provided in the signal processing unit 6. For example, the image output circuit 53 is connected to a personal computer and a part thereof is provided therein. In addition, for example, when the fingerprint data is stored but the personal identification is not performed, the personal identification unit 64 can be omitted.

Next, the relationship between the irradiation region (position) of the light 30 from the light source 3 and the brightness of the obtained fingerprint image will be described with reference to FIGS. However, the case where the light from the light source 3 is irradiated by one spot is demonstrated here.
4 to 6 are diagrams showing fingerprint images taken by the CCD when the light (laser light) 30 is spot-irradiated to the points A to D in FIG. 8, and FIG. 4 shows a point A in FIG. 5 shows a fingerprint image when the laser beam 30 is irradiated to the point B in FIG. 8, FIG. 6 shows the point C in FIG. 8, and FIG. 7 shows the point D in FIG. 4 to 7, the right side in the figure is the toe side (the tip side of the fingertip portion 1). FIG. 8 is a diagram illustrating irradiation points A to D of the light 30 on the back side of the fingertip portion 1.
In FIG. 4, the brightness is almost uniform over the entire surface of the fingerprint image, but in FIG. 5, the toe side (tip side of the fingertip part) close to the irradiation region 16 (point B) is saturated, and FIG. The toe side far from the point C) is dark. As for the width direction of the fingertip portion 1, it can be seen from FIG. 7 that the portion near the irradiation region 16 (point D) is saturated and the opposite side is dark.

  From these results, in order to obtain a fingerprint image with substantially uniform brightness over almost the entire area including fingerprint information necessary for personal identification, point A in FIG. It can be seen that it is preferable to irradiate a portion other than the substantially nail 12 on the substantially center line in the width direction on the surface where the nail exists and on the opposite side of the nail 12 with respect to the nail 12.

More specific irradiation areas 16 include, for example, point A (spot area) in FIG. 8, first irradiation area 161, second irradiation area 162, and third irradiation area 163 shown in FIG. 9. .
The first irradiation region 161 is a region in which the longitudinal direction extends from the point P at the nail to the first joint in the root direction, and the width does not exceed the width of the fingertip part 1. There is a center in the longitudinal direction at a position of about ½ of the length to one joint.
The second irradiation region 162 has a longitudinal direction at a position that is approximately ¾ of the length from the point P at the base side of the nail to the first joint in the longitudinal direction. The region is slightly at the tip, and the width is approximately 1/3 of the finger width, and the center in the longitudinal direction is at a position approximately 1/3 of the length from the point P at the nail to the first joint.
The third irradiation region 162 has a longitudinal direction at a position that is approximately 1/5 of the length from the point P at the base side of the nail to the first joint in the longitudinal direction. The region is slightly at the tip, and the width is approximately 1/5 of the finger width, and the center in the longitudinal direction is at a position approximately 1/10 of the length from the point P at the nail to the first joint.
In addition, although it is preferable that the edge part of the front end side of a longitudinal direction corresponds with the point P at the time of a nail | claw, you may catch on the nail | claw 12 somewhat. If the length from the point P at the nail to the tip of the fingertip part 1 is L, the tip end on the tip side in the longitudinal direction is preferably about 1/3 of the length L from the point P at the nail. Preferably it is up to about 1/4, and more preferably the upper nail skin (the part corresponding to the cuticle of the nail).

Furthermore, examples of the shape of the irradiation region 16 include an oval shape and a rectangular shape inscribed in the region.
In addition, even if each irradiation area | region 161-163 consists of several irradiation spots which can cover the whole region, the same result is obtained.

  Further, since near infrared light has a low transmittance in the blood of the living body, the blood vessel pattern inside the fingertip portion 1 is superimposed on the concave-convex pattern of the fingerprint 11 in the fingerprint image output from the imaging means 5, and the brightness decreases. It may cause a decrease in contrast. When a part that is extremely darker than the others is seen, it is also possible to take an image with a strong shading in order to brighten the part. For example, when the image brightness of the part on the toe side of the fingertip part 1 is low, the light 30 from the light source 3 is intentionally irradiated so as to cover the nail 12, and the brightness and the gain of the image pickup device are adjusted as necessary. If the image of the part 1 with the low lightness of the image on the toe side is imaged so that the lightness is appropriate, the contrast of the low lightness part can be improved. In this way, the shading can be controlled by moving the irradiation region (position) of the light 30 to the fingertip portion 1, and partial contrast can be improved.

Next, the operation will be described.
First, the marker light 31 is turned on with a light amount that is easy to see, and the image sensor 52 captures images at predetermined intervals.
When the fingertip part 1 is moved so that the marker light 31 is irradiated to a predetermined position and the fingertip part 1 blocks the marker light 31, the marker light 31 that has been captured by the image sensor 52 is blocked. The obtained image has a certain range below a certain brightness. An image obtained by the image sensor 52 is captured from the image output circuit 53 to the signal processing unit 6 by the image capturing unit 61 of the signal processing unit 6. Further, a predetermined range on the image sensor 52 (image obtained by the image sensor 52) that is sent from the image capturing unit 61 to the finger presence determination unit 65 and is blocked by the fingertip unit 1. If the lightness is within a predetermined threshold range, it is determined that the fingertip portion 1 exists in the imaging range of the imaging device 52.

  At the same time, the user moves the fingertip part 1 while visually confirming that the marker light 31 hits the optimum position of the fingertip part 1, so that the irradiation position optimization of the light 30 of the light source 3 to the fingertip part 1 is performed. It is also possible to optimize shading and increase the efficiency of the irradiation light quantity with respect to the image brightness.

When the finger presence determination unit 65 determines that the fingertip unit 1 is in the imaging range of the image sensor 52, the finger presence determination unit 65 sends a signal to the light source driving circuit 32 to project the light 30 that can pass through the fingertip unit 1, and from the light source 3. The light source 3 is turned on by adjusting the number of elements to be turned on and the brightness per element so that the light 30 has a predetermined brightness. The marker light source 33 may be turned off when the light source 3 is turned on, or may be turned on as it is.
The light 30 irradiated on the back surface (the surface opposite to the fingerprint 11) of the fingertip part 1 passes through the inside of the finger and reaches the fingerprint 11. The internal tissue near the surface on the ventral side of the fingertip part 1 has a transmittance distribution corresponding to the unevenness of the fingerprint 11 on the surface, and the light transmittance of the internal tissue corresponding to the convex part of the fingerprint is low, and the internal structure corresponding to the concave part Since the light transmittance of the tissue is high, the brightness of the light transmitted through the latter is higher than that of the former.

  Lens 41 and diaphragm 42 of optical system 4 optically designed so that light having an intensity distribution according to fingerprint 11 that has passed through fingertip 1 is telecentric toward the object (fingertip 1 that is the subject). Thus, an image is formed on the image sensor 52. A wavelength selection element 51 is disposed between the aperture 42 and the imaging element 52, and only light having the same wavelength as that of the light source 3 (red light to near-infrared light region) is selected. The image output circuit 53 receives an electrical signal from the image sensor 52, and outputs a fingerprint image having a valley (concave portion) brighter than a crest portion (convex portion) of the fingerprint as an image electrical signal.

  The fingerprint image obtained in this way by the imaging means 5 is captured by the image capturing unit 61 provided in the signal processing unit 6 and sent to the image processing unit 62. The image processing unit 62 performs image processing such as binarization and thinning on the fingerprint image as described in Japanese Patent Laid-Open No. 10-334237, for example, and extracts fingerprint feature information (fingerprint information). The extracted data is stored in the fingerprint data storage unit 63 as necessary. The personal identification unit 64 compares the data output from the image processing unit 62 with the data stored in the fingerprint data storage unit 63 to identify an individual.

Next, adjustment of the brightness of the fingerprint image and superposition or partial pasting of a plurality of fingerprint images having different brightness values taken on the same subject will be described.
In the present embodiment, the light 30 from the light source 3 is used in order to obtain a fingerprint image in which light and dark contrast is known with appropriate brightness in a range including fingerprint information necessary for personal identification, which is a main part of the fingerprint image. The irradiation center is on the approximate center line in the width direction on the surface of the fingertip portion 1 where the nail 12 is present and on the opposite side of the nail 12 from the nail 12, except for the nail 12. (Irradiation region 16 such as the first to third irradiation regions 161 to 163 described above) is irradiated.

However, there is still a part where the peak and valley of the fingerprint cannot be distinguished because the brightness is saturated or the brightness is too low in the range that contains the fingerprint information necessary for personal identification, which is the main part of the fingerprint image. In some cases, the fingerprint image cannot extract information necessary for personal identification.
Therefore, in the present embodiment, for example, before the image processing unit 62 extracts the feature information of the fingerprint, the lightness determination unit 66 determines whether the lightness of the fingerprint image is excessive or insufficient, and the lightness is excessive or insufficient. In order to obtain an image having an appropriate brightness, the image is picked up again by adjusting at least one of the irradiation condition (the luminance of the light source 3 and the irradiation area) and the gain of the image sensor 52 so as to collect an image having an optimal brightness. I have to.

  In addition, in order to obtain appropriate brightness within the range that includes fingerprint information necessary for personal identification, which is the main part of the fingerprint image, it is possible to take multiple images by adjusting multiple times instead of adjusting only once. is there. In addition, even when the range including the fingerprint information necessary for personal identification, which is the main part of the above-described fingerprint image, satisfies the appropriate brightness, the image quality can be further improved and the contrast can be improved. Adjustment and imaging may be repeated several times.

Hereinafter, a case where a plurality of images are collected will be described as an example. Light 30 is emitted from the light source 3 at a predetermined brightness and irradiation region 16, and the first imaging is performed with a predetermined gain of the image sensor 52. The image is sent from the image capturing unit 61 to the lightness determination unit 66, where the overall lightness of the range including the fingerprint information necessary for personal identification, which is the main part of the fingerprint image, is determined. As described above, at least one of the brightness adjustment of the light source 3 by the light source drive circuit 32 and the adjustment of the irradiation region and the gain adjustment by the gain adjustment circuit 55 is performed, and imaging is performed again.
Here, the overall brightness is determined based on the overall brightness not including position information for each pixel such as a histogram, or the brightness of a narrow range such as the brightness of a specific part or a small number of profiles. It refers to a case and may include a part that is partially too bright or too dark.

An image in which the overall brightness of the area including the range including the fingerprint information necessary for personal identification, which is the main part of the fingerprint image, is divided into a plurality of partial areas by the brightness determination unit 66, and the image of each partial area Judge the brightness. The plurality of partial areas include various areas such as each area obtained by dividing the entire area into two parts such as the tip side and the base side, and a plurality of areas including at least one pair of at least a fingerprint crest and valley from the entire area. Can be considered.
When all of the plurality of partial areas obtained in this way satisfy appropriate brightness within a predetermined threshold range, the image information of the image is sent to the image processing unit 62 for personal identification or fingerprint data Extract fingerprint information for storage.

  Further, in each partial area, when there is at least one location where the brightness of the image is outside the predetermined threshold range, the light source driving circuit 32 causes the entire partial area to have an appropriate brightness. Imaging is performed again after performing at least one of the adjustment of the luminance of the light source 3, the irradiation area, and the gain adjustment by the gain adjustment circuit 55, the image is captured from the image capturing unit 61, and temporarily stored. The above operation is performed over all the partial areas where there is at least one location where the brightness of the image is outside the predetermined threshold range, and the obtained image is temporarily stored in the image capturing unit 61.

  Next, the temporarily stored image is sent from the image capturing unit 61 to the image processing unit 64, and a partial region that satisfies a proper brightness within a range of a predetermined threshold is superimposed or superimposed with a plurality of images. Processing such as cutting out and pasting them together is performed to obtain an image with appropriate brightness over the entire surface including fingerprint information necessary for personal identification.

  In the above-described example, a plurality of images with appropriate overall brightness of a region including a range including fingerprint information necessary for personal identification, which is a main part of the fingerprint image, or brightness of a predetermined specific part are appropriate. The image brightness of each partial area is determined by dividing it into partial areas, and it is determined whether or not to capture a plurality of images. However, the irradiation conditions and the imaging are determined from the beginning without determining the image brightness of each partial area. A plurality of images having different brightness values with at least one of the gains of the element 52 may be captured.

  In this case, for example, two or more lightness threshold values at the time of the first lightness determination after the first imaging are determined, and the brightness and irradiation of the light source 3 are set to obtain the image lightness corresponding to each threshold value. There is a method of imaging a plurality of images by determining the position, the irradiation area, and the gain value of the image sensor 42. That is, a threshold value that makes the appropriate brightness of almost the entire range including the fingerprint information necessary for personal identification, a threshold value that eliminates a portion that is too dark instead of being brighter than the appropriate brightness value, and an appropriate brightness value. A threshold value that eliminates the saturated portion instead of darkening can be considered. The plurality of images obtained in this way are superimposed or bonded as described above to form one image.

  In any of the above-described examples, in the case of the first imaging, the light source 3 is used to obtain a fingerprint image with almost uniform brightness over almost the entire surface including the fingerprint information necessary for personal identification. As described above, the irradiation center of the light 30 is on the substantially center line in the width direction on the surface of the fingertip portion 1 where the nail 12 is present, and on the opposite side of the nail 12 from the hairline of the nail 12 Therefore, it is preferable to irradiate a portion other than the substantially nail 12 (irradiation regions 16 such as the first to third irradiation regions 161 to 163 described above).

  Note that the image that is superimposed or pasted by the image processing unit 62 may be an image before processing such as binarization or an image after processing.

  In addition, when a plurality of images with different brightness values captured with respect to the same subject as described above are superimposed or pasted together, it is important to shorten the imaging interval as much as possible in order to prevent displacement of the fingertip portion 1.

  In the above description, a case has been described in which a plurality of images with different brightness captured on the same subject are superimposed or laminated. However, the light 30 from the light source 3 is used as the first to third irradiation regions 161 as described above. Obtained when it is determined that the overall brightness of the range including the fingerprint information necessary for personal identification, which is the main part of the fingerprint image, obtained by irradiating the irradiation region 16 such as ˜163 is appropriate. Individual identification may be performed using the fingerprint image as it is.

  In the first embodiment, as a result of adjusting the brightness of the image by adjusting at least one of the light irradiation condition (luminance, irradiation region 16) and the gain of the imaging means 5 (imaging element 52), the fingerprint image If a fingerprint image that shows light and dark contrast with a more appropriate brightness within the range that contains fingerprint information necessary for personal identification, which is the main part, is obtained, multiple fingerprint images with different brightness for the same subject are superimposed or There is no need to paste them together.

  As described above, according to the present embodiment, the fingertip portion 1 having the fingerprint 11 to be imaged is the subject, the light source 3 that irradiates the subject with the light 30 that can pass through the subject, and the subject. An imaging unit 5 that captures the light from the light source 3 that is transmitted to obtain a fingerprint image in which the convex portion of the fingerprint 11 is dark and the concave portion is bright, and an optical system that forms an image on the image sensor 52 from the light source 3 that passes through the subject. 4, the light from the light source 3 irradiates a plurality of regions of the fingertip portion 1, and at least one of the plurality of regions has the irradiation center of the light 30 from the light source 3 as the fingertip portion 1. The skin of the fingerprint 11 is on the substantially center line in the width direction on the surface where the nail 12 is present and on the opposite side of the nail 12 with respect to the hairline of the nail 12 and irradiates a portion other than the substantially nail 12. Irregularity of fingerprint 11 is unknown regardless of surface moisture In this case, it is possible to obtain a stable fingerprint image and obtain a fingerprint image with an appropriate brightness and a contrast of light and darkness in a range including fingerprint information necessary for personal identification, which is a main part of the fingerprint image. It is possible to obtain accurate fingerprint information by preventing deterioration of the fingerprint image due to brightness. In addition, since the light from the light source illuminates a plurality of areas of the fingertip part, even if the installation position of the fingertip part is slightly shifted, the light from the light source is constantly radiated in the vicinity of the optimum irradiation position, so a fingerprint image with good contrast Can be obtained stably.

  A means (lightness determination unit 66, light source drive circuit 32, gain adjustment circuit 55) for adjusting the brightness of the image by adjusting at least one of the light irradiation condition and the gain of the imaging means 5 (imaging device 52); Since it includes means (image processing unit 62) for superimposing or partially pasting a plurality of fingerprint images of different brightness on the same subject, it includes fingerprint information necessary for personal identification, which is the main part of the fingerprint image In this range, it is possible to obtain a fingerprint image in which the contrast of light and darkness can be obtained with a more appropriate brightness, and it is possible to more reliably prevent deterioration of the fingerprint image due to the brightness and to obtain more accurate fingerprint information.

  In addition, the fingerprint image output from the imaging means 5 is subjected to image processing to obtain fingerprint information, and the signal processing unit 6 for identifying an individual based on the fingerprint information is provided. Improved personal identification.

  Further, since the marker light source 33 for irradiating the subject with the marker light 31 for positioning the subject is provided, an effect that the subject can be easily positioned on the apparatus main body can be obtained.

  In the above embodiment, the fingertip portion 1 is brought to the optimum irradiation position by the marker light 31. However, in the fingerprint image capturing apparatus of the present embodiment, the light from the light source 3 covers a plurality of regions of the fingertip portion. Since it is configured to irradiate, even if the installation position of the fingertip portion is slightly deviated, light from the light source is constantly radiated in the vicinity of the optimum irradiation position, so that the contrast is good even without positioning by the marker light 31 A fingerprint image can be obtained stably.

Moreover, although the case where the lens 41 was used as an image formation means was demonstrated in the said embodiment, you may use the pinhole etc. which have an image formation function besides an image formation lens.
Even when the lens 41 is used as the imaging means, the optical system 4 does not necessarily have to be telecentric.

Further, in the above embodiment, since near infrared light has low transmittance in the blood of living body, the blood vessel pattern inside the fingertip portion 1 is superimposed on the fingerprint uneven pattern in the fingerprint image output from the imaging means 5. Yes. Therefore, the blood vessel pattern may be removed from the fingerprint image output from the imaging means 5 as follows.
That is, first, a fingerprint image output from the imaging unit 5 is used as an original image, and a smoothing process is performed on the original image to obtain a smoothed image. Since the uneven pattern of the fingerprint has a narrower line width than the blood vessel pattern, the uneven pattern of the fingerprint is removed and the blood vessel pattern remains in the smoothed image. When the difference calculation between the original image and the smoothed image is performed, a fingerprint image in which only the concave / convex pattern of the fingerprint remains is obtained, and the feature information of the fingerprint is extracted from the fingerprint image.

  In the above description, the fingerprint image obtained by the imaging unit 5 is processed by the signal processing unit 6 to identify the individual. However, even if the fingerprint image is simply obtained without identifying the individual. Needless to say, it is good.

In order to reduce the overall size of the apparatus, as shown in FIG. 10, a plane mirror 8 is installed as a reflecting means so as to deflect the light transmitted through the fingertip 1, and the optical system 4, the wavelength selection element 51, and the imaging. The element 52 may be installed so as to face the deflected light. In FIG. 10, the signal processing unit 6 is omitted.
Note that the reflecting means is not limited to the plane mirror 8, and for example, a curved mirror can be used to reduce image distortion and aberration.
Further, a plurality of reflecting means may be provided to further reduce the size.
Further, the plane mirror 8 does not necessarily need to be between the lens 42 and the fingertip unit 1, and may be between the image sensor 42 and the fingertip unit 1, for example, between the lens 41 and the diaphragm 42.
Also in each of the following embodiments, although not particularly specified, the entire apparatus can be reduced in size by providing the reflection means so as to deflect the light transmitted through the fingertip portion 1 as in FIG.

  The subject holding unit 2 that can hold the surface of the fingerprint to be imaged in a non-contact state is not limited to the one having the frame shape shown in FIGS. 1 and 2, for example, as shown in FIG. A rod-shaped object arranged to support the fingertip part 1 in the vicinity of the first joint outside the observation surface 100 of the fingertip part 1 or an observation surface 100 sandwiched outside the observation surface 100 as shown in FIG. Can be used as at least a pair of rods arranged opposite to each other.

Embodiment 2. FIG.
FIG. 13 is a diagram for explaining the fingerprint image capturing apparatus according to the second embodiment of the present invention. More specifically, FIG. 13 is a side view showing the overall configuration of the fingerprint image capturing apparatus. In the following, differences from the first embodiment will be mainly described.

In the present embodiment, the subject holding unit 2 is not the subject holding unit 2 with an opening that can hold the fingertip unit 1 shown in the first embodiment while the surface of the fingerprint 11 to be imaged is in a non-contact state. A transparent object holding part 2 (hereinafter referred to as a transparent object holding part) 2 without an opening that can hold the fingertip part 1 in a state where the surface of the fingerprint 11 to be imaged is in contact is used. Unlike the first embodiment, the other configuration is the same as that of the first embodiment.
The operation is also the same as in the first embodiment, and the same effect as in the first embodiment can be obtained.

  However, in order to obtain a fingerprint image in which the convex portion of the fingerprint 11 is dark and the concave portion is bright by imaging the light from the light source 3 that transmits the convex portion of the fingerprint 11 and the light from the light source 3 that transmits the concave portion of the fingerprint 11 On the fingerprint contact surface of the subject holding unit 2, the critical angle of total reflection determined by the refractive index of the gas between the fingerprint recess and the transparent subject holding unit 2 and the refractive index of the transparent subject holding unit 2 is below. It is necessary to detect light incident on the transparent object holding part 2 in the direction of.

Embodiment 3 FIG.
In each of the above-described embodiments, the case where the subject holding unit 2 that can hold the fingertip unit 1 has been described. However, the subject holding unit 2 may not necessarily be provided.
The present embodiment is different from the first embodiment in that the subject holding unit 2 is not provided and the fingertip portion corresponding to the subject is not in contact with the structure, and other configurations are the same as in the first embodiment. Same as 1.
Even in such a configuration, the same effect as in the first embodiment can be obtained.

Embodiment 4 FIG.
14 and 15 are diagrams for explaining a fingerprint image imaging apparatus according to Embodiment 4 of the present invention. More specifically, FIG. 14 is a side view showing the overall configuration of the fingerprint image imaging apparatus, and FIG. FIG. 5 is a bottom view showing a state in which the vicinity of the fingertip portion is viewed from the imaging system side (abdominal side).

In the following, differences from the first embodiment will be mainly described.
In the present embodiment, unlike the first embodiment, there is no subject holding portion 2 with an opening, and instead, in order to measure the distance from the image sensor 53 of the fingertip portion 1 (the ventral side of the fingertip portion 1), A slit light source 71 and a slit light source driving circuit 72 for irradiating the slit light 70 are installed, and a finger position measuring unit 67 is provided in the signal processing unit 6. Other configurations are the same as those of the first embodiment.

When the light source drive circuit 72 for slit light receives a signal from the finger presence determination unit 65 that the fingertip unit 1 is present in the imaging range of the image sensor 52, the slit light source 71 is turned on and the slit light 70 is transmitted to the fingertip unit 1. Is irradiated on the ventral side (the surface of the fingerprint 11). The light source 71 for slit light is installed so that the slit light 70 passes through a range where the optical system 4 and the imaging system 5 are in focus.
The reflected light of the slit light 70 irradiated on the ventral side (the surface of the fingerprint 11) of the fingertip unit 1 is incident on the image sensor 52, converted into an image electrical signal by the image output circuit 53, and an image capturing unit of the signal processing unit 6. 61.
The slit light source 71 for projecting the slit light 70 is composed of, for example, a light emitting diode and a slit having a high directivity, a semiconductor laser, and a slit. In the case of a slit, one or more slit lights can be projected. Note that the shape of the slit light source 71 is not limited to a slit-like continuous straight line, and is a point, a sequence of dots that line up on the straight line, a lattice shape, a random pattern, and the distance from the object surface by the principle of triangulation. Various patterns that can be used for measurement can be used.

  The finger position measuring unit 67 receives a signal from the image capturing unit 61, and outputs a signal to the light source driving circuit 32 if the ventral side (observation surface 100) of the fingertip unit 1 is within the subject depth of the optical system 4. The light source 3 is turned on.

Next, the operation will be described.
In the first embodiment, positioning is performed by holding the fingertip unit 1 on the subject holding unit 2 with the opening. In the present embodiment, positioning is performed by irradiating the slit light 70 and measuring the position. .

The process is the same as in the first embodiment until it is determined by the finger presence determination unit 65 that the fingertip unit 1 has entered the imaging range of the optical system 4 and the imaging system 5 and is ready for imaging. Next, in the above-described state, a signal is sent from the finger presence determination unit 65 to the slit light source driving circuit 72, and the slit light source 71 emits the slit light 70.
For example, if two slit lights are lit as shown in FIG. 15 as the slit light 70, the position where the reflected light is incident on the image sensor 52 is obtained by image processing in the signal processing unit 6 for each slit. The distance between the image sensor 52 and the position irradiated with the slit light 70 on the observation surface 100 is obtained by the finger position measurement unit 67 by the triangulation method.
As the distance value, for example, the shortest distance, the average distance, and the least square distance are used for each slit light according to the trade-off between the calculation amount and the accuracy.
It should be noted that the distance between the position where the slit light 70 is irradiated on the observation surface 100 and the image sensor 52 can be obtained in the same manner even with point-sequence light according to the slit light.

If the result measured by the finger position measuring unit 67 is within the subject depth of the optical system 4 and the imaging system 5, the finger position measuring unit 67 sends a signal to the slit light source driving circuit 72, and the slit light source 71. Is turned off, a signal is sent from the finger position measurement unit 67 to the light source drive circuit 32, the light source 3 is turned on with a predetermined light amount that can be transmitted through the fingertip unit 1, and a fingerprint image by the transmitted light is captured.
The light source 71 for slit light may be turned off when the light source 3 is turned on, or may be turned on as it is.

  Thus, according to the present embodiment, the position measurement light (on the surface of the fingerprint 11 to be imaged of the subject 1 in which the surface of the fingerprint 11 to be imaged is not in contact with the structure) The light source 71 for slit light that irradiates the slit light 70) is provided, and the reflected light of the slit light 70 irradiated on the surface of the fingerprint 11 is photographed by the imaging means 5, and the distance of the surface of the fingerprint 11 to the optical system 4 is detected. Thus, it is possible to detect the position of the surface of the fingerprint 11 without touching the surface of the fingerprint 11 of the fingertip portion 1 and to take an image in a state where the fingerprint 11 is at the optimum position.

  FIG. 14 shows the case where the fingertip portion 1 is completely non-contact with no contact with the structure. However, for example, a rod-shaped subject holding portion is provided on the root side of the fingertip portion 1 with respect to the fingerprint 11 portion. In addition to the above effects, the position of the subject can be determined to some extent.

Embodiment 5 FIG.
FIG. 16 is a side view showing the overall configuration of the fingerprint image capturing apparatus according to the fifth embodiment. In the fourth embodiment, the slit light 70 is used for position measurement instead of not providing the subject holding unit 2. However, in the present embodiment, the slit light 70 is also used for finger rest determination. In this case, one or more slit lights 70 are sufficient. The same is true until the finger position measuring unit 67 measures the position of the fingertip 1, but if the result measured by the finger position measuring unit 67 is within the subject depth of the optical system 4 and the imaging system 5, the finger position measurement is performed. A signal is sent from the unit 67 to the finger rest determination unit 68. The finger stationary determination unit 68 compares the positional deviation of the slit light 70 on the reflected light image of the predetermined number of slit lights 70 captured at a predetermined time interval, and the predetermined time until the deviation falls within a predetermined range. A signal is sent to the image capturing unit 61 at intervals, and the image capturing determination is continued. If the deviation is within a predetermined range, it is determined that the subject 1 is stationary. If it is determined that the subject 1 is stationary, a signal is sent to the light source drive circuit 32 to project the light 30 that can pass through the fingertip unit 1, and the light 30 from the light source 3 is set to a predetermined brightness. The light source 3 is turned on by adjusting the number of elements to be lit and the brightness per element. Subsequent operations are the same as those in the fourth embodiment.
In this embodiment, since the image is taken after it is determined that the finger is stationary, it is possible to suppress finger shake and the like.

Embodiment 6 FIG.
FIG. 17 is a side view showing the overall configuration of the fingerprint image capturing apparatus according to the sixth embodiment. In the fourth embodiment, the position measurement is performed using the slit light 70 instead of providing the subject holding section 2. However, in the present embodiment, the slit light 70 is used to perform the measurement even when the subject holding section 2 exists. Position measurement was performed in the same manner as in Embodiment 4.
Thereby, even when the placement of the fingertip 1 on the subject holding unit 2 is not stable, the positioning can be performed more precisely.

FIG. 18 is a side view showing the overall configuration of another fingerprint image capturing apparatus according to the sixth embodiment. In the fingerprint image capturing apparatus shown in FIG. 18, even when the subject holding unit 2 is present, position measurement is performed using the slit light 70, and the slit light 70 is also used for determining finger rest.
Accordingly, even when the placement of the fingertip 1 on the subject holding unit 2 is not stable, it is possible to perform positioning more precisely, and since it is determined that the finger is stationary, the image is taken. You can reduce the blurring.

FIG. 19 is a side view showing the overall configuration of still another fingerprint image capturing apparatus according to the sixth embodiment. In the fingerprint image capturing apparatus shown in FIG. 18, the finger position determination and the finger stationary determination are performed by the slit light 70. However, since the subject holding unit 2 is provided, the position and angle of the fingertip 1 can be easily determined. . Therefore, in the fingerprint image capturing apparatus shown in FIG. 19, only the finger stillness determination is performed by the slit light.
As a result, since it is determined that the finger is stationary and the image is taken, blurring of the finger can be suppressed.

  In FIGS. 17 to 19, the subject holding portion 2 with an opening having a frame shape is shown as the subject holding portion. However, the position of the fingertip portion 1 can be determined, and the surface of the fingerprint 11 is not Any device can be used as long as it can hold the fingertip portion 1 in a contact state. For example, as shown in FIG. 11, an observation is made outside the observation surface 100 in order to hold the ventral tip portion and the ventral root portion of the fingertip portion 1. It is also possible to use at least a pair of rod-shaped object holding parts 2 or the like disposed so as to face each other with the surface 100 interposed therebetween.

Embodiment 7 FIG.
Next, an embodiment in which the present invention is applied to a fingerprint image capturing apparatus having a configuration different from those in Embodiments 1 to 6 will be described.
In the previous application (Japanese Patent Application No. 2004-290574), the inventors of the present invention use a fingertip portion having a fingerprint to be imaged as a subject, and irradiate the subject with light that can be transmitted therethrough. Corresponding to the fingerprint, imaging the light from the light source and the light from the light source that transmits the convex portion of the fingerprint and the light from the light source that transmits the concave portion of the fingerprint, the convex portion of the fingerprint is dark and the concave portion is bright In a fingerprint image imaging apparatus comprising an imaging means for obtaining a fingerprint image and an optical system for imaging light from the light source that passes through the subject on the imaging means, a surface orthogonal to the optical axis of the optical system. With reference to the position where the back side or the abdominal side of the fingertip part is in contact, the tip side of the fingertip part of the subject is separated from the optical system by a predetermined angle (about 10 ° to about 10 ° to By tilting 30 °), it is perpendicular to the optical axis of the optical system. It has been disclosed that the contrast of the fingerprint image can be further improved as compared with the case where the back side or the abdominal side of the fingertip part is brought into contact with the surface.
This is thought to be because the transmittance characteristics of the fingerprint surface and the internal tissue in the vicinity of the fingerprint surface are angularly dependent, and light is easily transmitted at a specific angle.

  In the seventh embodiment, a light from a light source irradiates a plurality of regions of a fingertip portion with respect to a fingerprint image capturing apparatus configured with attention paid to the above characteristics.

  20 to 23 are views for explaining a fingerprint image imaging apparatus according to Embodiment 7 of the present invention. More specifically, FIG. 20 is a side view showing the overall configuration of the fingerprint image imaging apparatus, and FIG. FIG. 22 is a bottom view showing the vicinity of the fingertip portion as seen from the imaging means side (abdominal side), and FIG. 22 and FIG. 23 are top views showing the vicinity of the fingertip portion as seen from the back side (nail side).

The fingerprint image capturing apparatus according to the present embodiment has a fingertip 1 having a fingerprint 11 to be imaged as an object, and a light source 3 that irradiates the object 1 with light 30 that can pass through the object 1 and a plurality of irradiation spots. ,
Imaging means 5 for imaging the light from the light source 3 that passes through the subject 1 to obtain a fingerprint image corresponding to the fingerprint 11 in which the convex portion of the fingerprint 11 is dark and the concave portion is bright;
An optical system 4 for imaging the light from the light source 3 that passes through the subject 1 on the imaging means 5;
The fingerprint image output from the imaging means 5 is subjected to image processing to obtain fingerprint information, and a signal processing unit 6 for identifying an individual based on the fingerprint information is provided.
In addition, with reference to the position where the back side of the fingertip portion is brought into contact with the surface 402 orthogonal to the optical axis 400 of the optical system 4, the subject 1 is separated from the optical system 4 by comparing the tip side of the fingertip portion with the opposite side. The optical system 4 was arranged so as to be inclined at a predetermined angle so as to leave.

In the seventh embodiment, the subject holding section (hereinafter referred to as an apertured subject) is tilted with respect to the optical system so that the position and the angle of the subject 1 with respect to the optical system 4 become a predetermined position and a predetermined angle. This is referred to as a specimen holding unit 21.) 2 is installed. The opening part of the subject holding unit 21 with the opening is provided so as to include the observation surface 100 that is a range imaged by the imaging unit 5.
The light source 3 is composed of one or more lasers, light emitting diodes, and lamp light sources, and can be turned on at an arbitrary number simultaneously. When the fingertip part 1 is held by the subject holding part 21 with an opening and the observation surface 100 is at a position that fits within the opening of the subject holding part 21 with an opening, for example, a predetermined region 16 of the fingertip part as shown in FIG. It arranges so that can be irradiated. In addition, the light source driving circuit 32 is configured to control the irradiation condition (luminance and irradiation region 16) of the light 30 irradiated to the subject 1 by controlling the element to be turned on. For example, when the light source 3 is composed of a plurality of light emitting elements, each element or a small group of elements configured to irradiate the same position (area) irradiates different positions (areas) of the fingertip 1. Install as described. Furthermore, the irradiation region 16 in the subject 1 is configured to be a plurality of regions, for example, by controlling an element to be turned on according to a position (region) to be irradiated. Controlling the irradiation region 16 means controlling the position, the size of the region, and the number of regions individually or in combination. When controlling the number of regions, a plurality of light sources 3 may be provided.
In the seventh embodiment, the configuration of each other part is the same as that of the first embodiment, and the description thereof is omitted.

As described in the first embodiment, in order to obtain a fingerprint image with substantially uniform brightness over almost the entire area including fingerprint information necessary for personal identification, point A in FIG. On the surface of the fingertip portion 1 where the nail 12 is present, on the substantially center line in the width direction and on the opposite side of the nail 12 from the nail 12 and irradiates the portion other than the nail 12. preferable. Even in the case where the observation surface on the ventral side of the fingertip 11 is inclined at a predetermined angle with respect to the surface 402 orthogonal to the optical axis 400 of the optical system 4 as in the seventh embodiment, the irradiation point and the fingerprint image The relationship with light and dark is the same as the above result.
More specifically, as in the first embodiment, for example, the point A in FIG. 8 (spot region), the first irradiation region 161, the second irradiation region 162, and the third irradiation region 16 shown in FIG. An irradiation region 163 is exemplified.
The first irradiation region 161 is a region in which the longitudinal direction extends from the point P at the nail to the first joint in the root direction, and the width does not exceed the width of the fingertip part 1. There is a center in the longitudinal direction at a position of about ½ of the length to one joint.
The second irradiation region 162 has a longitudinal direction at a position that is approximately ¾ of the length from the point P at the base side of the nail to the first joint in the longitudinal direction. The region is slightly at the tip, and the width is approximately 1/3 of the finger width, and the center in the longitudinal direction is at a position approximately 1/3 of the length from the point P at the nail to the first joint.
The third irradiation region 162 has a longitudinal direction at a position that is approximately 1/5 of the length from the point P at the base side of the nail to the first joint in the longitudinal direction. The region is slightly at the tip, and the width is approximately 1/5 of the finger width, and the center in the longitudinal direction is at a position approximately 1/10 of the length from the point P at the nail to the first joint.
In addition, although it is preferable that the edge part of the front end side of a longitudinal direction corresponds with the point P at the time of a nail | claw, you may catch on the nail | claw 12 somewhat. If the length from the point P at the nail to the tip of the fingertip part 1 is L, the tip end on the tip side in the longitudinal direction is preferably about 1/3 of the length L from the point P at the nail. Preferably it is up to about 1/4, and more preferably the upper nail skin (the part corresponding to the cuticle of the nail).

Furthermore, examples of the shape of the irradiation region 16 include an oval shape and a rectangular shape inscribed in the region.
In addition, even if each irradiation area | region 161-163 consists of several irradiation spots which can cover the whole region, the same result is obtained.

Next, a configuration in which the fingertip portion 1 is tilted by a predetermined angle to improve the contrast of the fingerprint image will be described. However, the case where the light from the light source 3 is irradiated by one spot is demonstrated here.
As shown in FIGS. 20 and 22, a straight line that passes through the vicinity of the center in the finger width direction on the nail side (back side) of the fingertip part 1 and contacts the back side of the fingertip part 1 is a straight line that represents the back side of the fingertip part. 15 is assumed. The subject holding unit 21 with the opening is based on the position where the back side of the fingertip unit 1 is brought into contact with the surface 402 orthogonal to the optical axis 400 determined by the optical system 4 when the fingertip unit 1 is held. The distal end side of the fingertip portion of the specimen 1 is installed so as to be inclined at a predetermined angle (θ) so as to be away from the optical system 4 (lens 41) compared to the opposite side. That is, the optical system 4 and the subject with an aperture are set so that the angle formed by the surface 402 orthogonal to the optical axis 400 of the optical system 4 and the straight line 15 representing the back side of the fingertip portion 1 is a predetermined angle (θ). A holding part 21 is arranged.

FIG. 24 shows the relationship between the angle (θ) formed by the straight line 15 representing the dorsal side of the fingertip and the plane 402 having the optical axis 300 as a perpendicular and the contrast of the fingerprint image.
25, using a sample (subject 1) different from that shown in FIG. 24 with the same configuration, the tip side of the fingertip portion 1 is closer to the optical system 4 than the opposite side (so that θ is negative). (B) shows the relationship between θ and contrast when tilted.
24 and 25, it is understood that the contrast of the fingerprint image is improved when the tilt angle θ is 10 ° to 30 °, more preferably 15 ° to 25 °, and still more preferably around 20 °.

In addition to the fact that the ventral side of the fingertip portion 1 is formed of a curved surface, the fingertip portion 1 is inclined with respect to the optical axis 400 of the optical system 4, so that the observation surface 100 has an angle with respect to the optical axis 400. It is difficult to focus on the entire observation surface 100. Therefore, the depth of the subject of the optical system 4 is increased so that the entire surface of the observation surface 100 is focused, and the image sensor 52 is inclined with respect to the optical axis 400 as shown in FIG.
As described above, the entire depth of the observation surface 100 of the fingertip unit 1 is within the subject depth of the optical system 4 by increasing the subject depth of the optical system 4 and tilting the imaging device 52 with respect to the optical axis 400. The image with good contrast can be obtained.

Next, the operation will be described.
First, the marker light 31 is turned on with a light amount that is easy to see, and the image sensor 52 captures images at predetermined intervals.
When the fingertip portion 1 is arranged so as to block the marker light 31, the light source 31 is blocked, so that a certain range of the image obtained by the image sensor 52 becomes a certain luminance or less. An image obtained by the image sensor 52 is captured from the image output circuit 53 to the signal processing unit 6 by the image capturing unit 61 of the signal processing unit 6. Further, a predetermined range on the image sensor 52 (image obtained by the image sensor 52) that is sent from the image capturing unit 61 to the finger presence determination unit 65 and is blocked by the fingertip unit 1. If the luminance is within a predetermined threshold range, it is determined that the fingertip portion 1 is in the imaging range of the imaging element 52.

  At the same time, when the user moves the fingertip part 1 while visually confirming that the marker light 31 hits the optimum position of the fingertip part 1, the fingertip is a condition in which the brightness is almost uniform over the entire fingerprint image. Since the light 30 from the light source 3 is projected onto one irradiation area 16, the shading is optimized by optimizing the irradiation position of the light source 3 on the fingertip portion 1, and the efficiency of the irradiation light quantity with respect to the image luminance is also increased. it can.

When the finger presence determination unit 65 determines that the fingertip unit 1 is within the imaging range of the image sensor 52, the finger presence determination unit 65 sends a signal to the light source driving circuit 32 to project light that can pass through the fingertip unit 1, and emits light from the light source 3. The light source 3 is turned on by adjusting the number of elements to be turned on and the brightness per element so that the light 30 has a predetermined brightness. The marker light source 33 may be turned off when the light source 3 is turned on, or may be turned on as it is.
The light 30 irradiated on the back surface (the surface opposite to the fingerprint 11) of the fingertip part 1 passes through the inside of the finger and reaches the fingerprint 11. The internal tissue near the surface on the ventral side of the fingertip part 1 has a transmittance distribution corresponding to the unevenness of the fingerprint 11 on the surface, and the light transmittance of the internal tissue corresponding to the convex part of the fingerprint is low, and the internal structure corresponding to the concave part Since the light transmittance of the tissue is high, the brightness of the light transmitted through the latter is higher than that of the former.

  Among the light having an intensity distribution according to the fingerprint 11 transmitted through the fingertip part 1, the angle (θ) between the straight line 15 representing the back side of the fingertip part 1 and the plane 402 is 10 ° to 30 °. The lens 41 and the diaphragm 42 of the optical system 4 are optically designed so that only light inclined at about 15 ° to 25 °, more preferably about 20 ° is telecentric toward the object (the fingertip portion 1 that is the subject). The image is formed on the image sensor 52. A wavelength selection element 51 is disposed between the aperture 42 and the imaging element 52, and only light having the same wavelength as that of the light source 3 (red light to near-infrared light region) is selected. The image output circuit 53 receives an electrical signal from the image sensor 52 and outputs a fingerprint image having a valley (concave portion) brighter than a fingerprint crest (convex portion) as an image electrical signal.

  The fingerprint image obtained in this way by the imaging means 5 is captured by the image capturing unit 61 provided in the signal processing unit 6 and sent to the image processing unit 62. The image processing unit 62 performs image processing such as binarization and thinning on the fingerprint image as described in Japanese Patent Laid-Open No. 10-334237, for example, and extracts fingerprint feature information (fingerprint information). The extracted data is stored in the fingerprint data storage unit 63 as necessary. The personal identification unit 64 compares the data output from the image processing unit 62 with the data stored in the fingerprint data storage unit 63 to identify an individual.

In the present embodiment, the signal processing unit 6 includes a lightness determination unit 66. For example, before the image processing unit 62 extracts the feature information of the fingerprint, the lightness determination unit 66 determines the lightness of the fingerprint image. Excessive or insufficient is determined, and at least one of the irradiation condition (the luminance of the light source 3 and the irradiation region 16) and the gain of the image sensor 52 are adjusted so as to collect an image with optimum brightness, and then imaging is performed again.
For this purpose, the lightness determination unit 66 determines whether the lightness of the fingerprint image output from the image capturing unit 61 is within a predetermined threshold range, and the light source is set to be within the predetermined threshold range. One or both of the drive circuit 32 and the gain adjustment circuit 55 are controlled, and the image pickup device 52 performs image pickup again. That is, when the brightness of the fingerprint image is lower than a predetermined threshold range, for example, an electric signal is sent to the light source driving circuit 32 so that the projection light 30 having the highest possible brightness is emitted in a range where the brightness is not saturated. When the light source 3 is driven and the brightness of the fingerprint image is higher than a predetermined threshold range, the light source 3 is driven so as to emit the projection light 30 having a low luminance.
Thus, by setting the threshold value of the brightness of the fingerprint image to an appropriate value, deterioration of the fingerprint image and the identification performance due to the brightness can be prevented.

  As described above, according to the present embodiment, the fingertip portion 1 having the fingerprint 11 to be imaged is the subject, the light source 3 that irradiates the subject with the light 30 that can pass through the subject, and the subject that passes through the subject. An imaging unit 5 that captures light from the light source 3 to obtain a fingerprint image in which the convex portion of the fingerprint 11 is dark and the concave portion is bright, and an optical system 4 that focuses the light from the light source 3 that passes through the subject on the imaging unit 5. The light from the light source 3 is configured to irradiate a plurality of regions of the fingertip 1 and the back side of the fingertip 1 is brought into contact with the surface 402 orthogonal to the optical axis 400 of the optical system 3. Since the optical system 3 is arranged so that the tip end side of the fingertip of the subject is inclined at a predetermined angle so as to be away from the optical system 3 relative to the opposite side with respect to the position, the skin surface of the fingerprint 11 Regardless of the humidity state of the fingerprint, even when the unevenness of the fingerprint 11 is unclear, There is an advantage that it is possible to obtain more improved fingerprint images of the trust. In addition, since the light from the light source illuminates a plurality of areas of the fingertip part, even if the installation position of the fingertip part is slightly shifted, the light from the light source is constantly radiated in the vicinity of the optimum irradiation position, so a fingerprint image with good contrast Can be obtained stably.

  Further, in addition to the above configuration, the fingerprint image output from the imaging means 5 is subjected to image processing to obtain fingerprint information, and the signal processing unit 6 for identifying an individual based on this fingerprint information is provided. Is obtained.

  Further, when the predetermined angle is 10 ° to 30 °, preferably 15 ° to 25 °, more preferably around 20 °, a fingerprint image with improved contrast can be obtained.

  Further, the light 30 from the light source 3 is irradiated on the substantially center line in the width direction on the surface of the fingertip portion 1 where the nail 12 is present, and on the side opposite to the nail 12 portion with respect to the line of the nail 12. Yes, since the portion other than the nail 12 is irradiated, a fingerprint image with appropriate brightness can be obtained in a range including fingerprint information necessary for personal identification, which is the main part of the fingerprint image, and the fingerprint image due to the brightness Thus, accurate fingerprint information can be obtained.

  In addition, since the subject holding unit 21 that can hold the subject in a state where the surface of the fingerprint to be imaged is not in contact is provided, the position and angle of the subject with respect to the optical system 3 can be easily adjusted. An effect is obtained.

  Further, since the marker light source 33 for irradiating the subject with the marker light 31 for positioning the subject is provided, an effect that the subject can be easily positioned on the apparatus main body can be obtained.

  In the above embodiment, the fingertip portion 1 is brought to the optimum irradiation position by the marker light 31. However, in the fingerprint image capturing apparatus of the present embodiment, the light from the light source 3 covers a plurality of regions of the fingertip portion. Since it is configured to irradiate, even if the installation position of the fingertip portion is slightly deviated, light from the light source is constantly radiated in the vicinity of the optimum irradiation position, so that the contrast is good even without positioning by the marker light 31 A fingerprint image can be obtained stably.

  In the above description, the case where the fingerprint image obtained by the imaging means 5 is processed by the signal processing unit 6 to identify an individual has been described. However, the present invention is also used when a fingerprint image is simply obtained without personal identification. Needless to say, you can.

  20 and 21, the subject holding unit 21 with an opening having a frame shape is shown as the subject holding unit that can hold the surface of the fingerprint to be imaged in a non-contact state. Any device can be used as long as it can determine the angle and position of the fingertip 1 and can hold the fingertip 1 with the surface of the fingerprint 11 in a non-contact state. For example, as shown in FIG. In order to hold the distal end portion and the ventral base portion, at least a pair of rod-shaped subject holding portions 22 and the like arranged opposite to each other with the observation surface 100 interposed therebetween may be used.

In order to reduce the overall size of the apparatus, as shown in FIG. 27, a plane mirror 8 is installed as a reflecting means so as to deflect the light transmitted through the fingertip portion 1, and the optical system 4, the wavelength selection element 51, The image sensor 52 may be installed to face the deflected light. In FIG. 27, the signal processing unit 6 is omitted.
Note that the reflection means is not limited to the plane mirror 8, and for example, a curved mirror can be used to reduce image distortion and aberration.
Further, a plurality of reflecting means may be provided to further reduce the size.
Further, the plane mirror 8 does not necessarily need to be between the lens 42 and the fingertip unit 1, and may be between the image sensor 42 and the fingertip unit 1, for example, between the lens 41 and the diaphragm 42.
Also in each of the following embodiments, although not particularly specified, the apparatus as a whole can be reduced in size by providing the reflecting means so as to deflect the light transmitted through the fingertip portion 1 as in FIG.

Embodiment 8 FIG.
28 and 29 are views for explaining a fingerprint image imaging apparatus according to the eighth embodiment of the present invention. More specifically, FIG. 28 is a side view showing the entire configuration of the fingerprint image imaging apparatus, and FIG. FIG. 5 is a bottom view showing a state in which the vicinity of the fingertip portion is viewed from the imaging system side (abdominal side).

Hereinafter, differences from the seventh embodiment will be mainly described.
In the present embodiment, unlike the seventh embodiment, the subject holding section 21 with an opening does not exist. Instead, the distance from the image sensor 53 of the fingertip portion 1 (the ventral side of the fingertip portion 1) and the observation surface 100 ( A slit light source 71 and a slit light source drive circuit for irradiating the slit light 70 in order to measure an angle formed by the flat surface 402 (a surface orthogonal to the optical axis 400 of the optical system 4) and the flat surface 402 of the fingertip 1 72 is provided, and a finger position measuring unit 67 is provided in the signal processing unit 6. Other configurations are the same as those of the seventh embodiment.

When the light source drive circuit 72 for slit light receives a signal from the finger presence determination unit 65 that the fingertip unit 1 is present in the imaging range of the image sensor 52, the slit light source 71 is turned on and the slit light 70 is transmitted to the fingertip unit 1. Is irradiated on the ventral side (the surface of the fingerprint 11). The light source 71 for slit light is installed so that the slit light 70 passes through a range where the optical system 4 and the imaging system 5 are in focus.
The reflected light of the slit light 70 irradiated on the ventral side (the surface of the fingerprint 11) of the fingertip unit 1 is incident on the image sensor 52, converted into an image electrical signal by the image output circuit 53, and an image capturing unit of the signal processing unit 6. 61.
The slit light source 71 for projecting the slit light 70 is composed of, for example, a light emitting diode and a slit having a high directivity, a semiconductor laser, and a slit. In the case of a slit, one or more slit lights can be projected. Note that the shape of the slit light source 71 is not limited to a slit-like continuous straight line, and is a point, a sequence of dots that line up on the straight line, a lattice shape, a random pattern, and the distance from the object surface by the principle of triangulation. Various patterns that can be used for measurement can be used.

  The finger position measuring unit 67 receives a signal from the image capturing unit 61, the ventral side (observation surface 100) of the fingertip unit 1 exists within the subject depth of the optical system 4, and is formed by the observation surface 100 and the plane 402. It is measured whether the angle is inclined by 10 ° to 30 °, more preferably 15 ° to 25 °, and still more preferably about 20 °. If the condition is satisfied, a signal is output to the light source driving circuit 32 and the light source 3 is turned on.

Next, the operation will be described.
In the seventh embodiment, positioning is performed by holding the fingertip unit 1 on the subject holding unit 21 with the opening. In the present embodiment, positioning is performed by irradiating the slit light 70 and measuring the position. .

The process is the same as in the seventh embodiment until it is determined by the finger presence determination unit 65 that the fingertip unit 1 has entered the imaging range of the optical system 4 and the imaging system 5 and is ready for imaging. Next, in the above-described state, a signal is sent from the finger presence determination unit 65 to the slit light source driving circuit 72, and the slit light source 71 emits the slit light 70.
For example, if two slit lights are lit as shown in FIG. 29 as the slit light 70, the position where the reflected light is incident on the image sensor 52 is obtained for each slit by image processing in the signal processing unit 6. The distance between the image sensor 52 and the position irradiated with the slit light 70 on the observation surface 100 is obtained by the finger position measurement unit 67 by the triangulation method. Further, since there are two or more slit lights, the observation surface 100 (more precisely, the fingertip portion 1 of each slit light 70 on the abdomen side is determined based on the relationship between the distance between the slit lights and the distance between the slit light and the image sensor 52. The plane 17 that passes through the irradiating portions 70a and 70b, and hereinafter, the plane 17 is referred to as the plane 17 representing the ventral side (observation plane) of the fingertip portion 1) and the plane 402 is obtained.
As the distance value, for example, the shortest distance, the average distance, and the least square distance are used for each slit light according to the trade-off between the calculation amount and the accuracy.
Note that the distance between the position where the slit light 70 is irradiated on the observation surface 100 and the imaging element 52 and the angle between the observation surface 100 and the plane 402 can be obtained in the same way even with point sequence light according to the slit light.

The result measured by the finger position measuring unit 67 is within the subject depth of the optical system 4 and the imaging system 5, and the angle between the observation surface 100 and the plane 402 is 10 ° to 30 °, more preferably 15 °. If it is ˜25 °, more preferably around 20 °, the finger position measuring unit 67 sends a signal to the slit light source driving circuit 72 to turn off the slit light source 71 and the finger position measuring unit 67 to the light source driving circuit. A signal is sent to 32, the light source 3 is turned on with a predetermined amount of light that can be transmitted through the fingertip portion 1, and a fingerprint image by the transmitted light is captured.
The light source 71 for slit light may be turned off when the light source 3 is turned on, or may be turned on as it is.

In the seventh embodiment, the tip side of the fingertip part of the subject is compared with the opposite side with respect to the position where the back side of the fingertip part 1 is brought into contact with the surface 402 orthogonal to the optical axis 400 of the optical system 4. By tilting a predetermined angle away from the optical system 4, that is, by setting the angle (θ) formed by the straight line 15 representing the back side of the fingertip portion 1 and the plane 402 to a predetermined angle, It has been explained that the contrast of fingerprint images is improved.
On the other hand, in the present embodiment, the tip side of the fingertip part of the subject is the opposite side with respect to the position where the ventral side of the fingertip part 1 is brought into contact with the surface 402 orthogonal to the optical axis 400 of the optical system 4. In other words, the angle (θ ′) formed by the plane 17 representing the ventral side (observation plane) of the fingertip portion 1 and the plane 402 is inclined by a predetermined angle so as to be separated from the optical system 4. It is described that the contrast of the fingerprint image is improved by setting the angle at a predetermined angle (10 ° to 30 °, preferably 15 ° to 25 °, more preferably around 25 °).

  The plane 17 representing the ventral side (observation surface) of the fingertip part 1 and the straight line 15 representing the back side of the fingertip part 1 are not parallel but have a slight angle, and there are individual differences in the angle. However, the angle (θ) between the straight line 15 representing the back side of the fingertip portion 1 described in the seventh embodiment and the surface 402 orthogonal to the optical axis 400 of the optical system 4 (10 ° to 30 °, Preferably, the angle between the plane 17 representing the ventral side (observation surface) of the fingertip part 1 and the straight line 15 representing the dorsal side of the fingertip part 1 and individual differences thereof are included. As in this embodiment, the angle (θ ′) between the plane 17 representing the ventral side (observation plane) of the fingertip portion 1 and the plane 402 is within the above range (10 ° to 30 °, preferably 15 ° to 25 °), a fingerprint image with improved contrast can be obtained as in the seventh embodiment in which the fingertip portion 1 is held by the subject holding portion 21 with opening or the rod-like subject holding portion 22.

  For the same reason as described above, also in the seventh embodiment, the opening surface (fingertip portion) surrounded by the surface of the subject holding portion 21 with opening or the rod-shaped subject holding portion 22 on the side where the fingertip portion 1 abuts. 1 is a predetermined angle (10 ° to 30 °, preferably 15 ° to 25 °) with respect to a surface 402 orthogonal to the optical axis 400 of the optical system 4. It may be arranged in the state.

  Thus, according to the present embodiment, the position measurement light (on the surface of the fingerprint 11 to be imaged of the subject 1 in which the surface of the fingerprint 11 to be imaged is not in contact with the structure) A slit light source 71 for irradiating the slit light 70) is provided, and the reflected light of the slit light 70 irradiated on the surface of the fingerprint 11 is photographed by the imaging means 5, and the distance of the surface of the fingerprint 11 with respect to the optical system 4 and optical Since the inclination angle from the surface 402 orthogonal to the optical axis 400 of the system 4 is detected, the position and shape (inclination angle) of the surface of the fingerprint 11 can be detected without contacting the surface of the fingerprint 11 of the fingertip portion 1. Thus, an image can be taken in a state where the fingertip portion 1 is at an optimum angle with respect to the optical axis 400 of the optical system 4, and a fingerprint image with improved contrast can be obtained.

  28 shows a case where the fingertip portion 1 is completely non-contact with no contact with the structure. However, for example, a rod-shaped subject holding portion is provided on the root side of the fingerprint 11 portion of the fingertip portion 1. In addition to the above effects, the position of the subject can be determined to some extent.

Embodiment 9 FIG.
30 and 31 are views for explaining a fingerprint image imaging apparatus according to Embodiment 9 of the present invention. More specifically, FIG. 30 is a side view showing the overall configuration of the fingerprint image imaging apparatus, and FIG. FIG. 4 is an enlarged view schematically showing a contact portion between a transparent subject holding portion and a subject.

Hereinafter, differences from the seventh embodiment will be mainly described.
In the seventh embodiment, the subject holding unit (the subject holding unit 21 with an opening or the rod-like subject holding unit 22) that can hold the fingertip unit 1 in a state where the surface of the fingerprint 11 to be imaged is not in contact is provided. However, in the present embodiment, a transparent subject holding portion (hereinafter referred to as a transparent subject holding portion) 23 that can hold a subject having a fingerprint in a state where the surface of the fingerprint to be imaged is in contact is provided. ing. Other configurations are the same as those of the seventh embodiment.

The transparent subject holding unit 23 is the same in installation position and function as the subject holding unit 21 with an opening in the seventh embodiment, except for the presence or absence of the opening. That is, they are installed so that θ and θ ′ are 10 ° to 30 °, preferably 15 ° to 25 °, more preferably around 20 °.
The operation is also the same as in the seventh embodiment, and the same effect as in the seventh embodiment is obtained.

  However, in order to capture the light from the light source 3 that transmits the convex portion of the fingerprint 11 and the light from the light source 3 that transmits the concave portion of the fingerprint 11 to obtain a fingerprint image in which the convex portion of the fingerprint 11 is dark and the concave portion is bright, As shown in FIG. 31, on the fingerprint contact surface of the transparent subject holding portion 23, the refractive index of the gas between the fingerprint recess 11 a and the transparent subject holding portion 23 and the refractive index of the transparent subject holding portion 23. It is necessary to detect light incident on the transparent object holding unit 23 in a direction equal to or smaller than the critical angle θ of total reflection determined by

For example, the gas between the fingerprint recess 11a and the transparent object holding part 23 is air, the transparent object holding part 23 is glass, the refractive index n0 of air is 1.0, and the refractive index ng of glass is 1. 5, the critical angle φ becomes φ = arcsin (n 0 / ng) = 41 (degrees), and the light that has passed through the fingerprint recess 11 a enters the transparent object holding part 23 at an angle within 41 degrees.
On the other hand, if the refractive index of the living body is 1.45, for example, arcsin (1.45 / 1.5) = 75 (degrees), and the light that has passed through the fingerprint convex portion 11b is transparent at an angle within 75 degrees. The light enters the sample holder 23.
Therefore, by detecting the light incident on the transparent object holding part 23 at an angle of 41 degrees or less, both the light transmitted through the fingerprint convex part 11b and the light transmitted through the concave part 11a can be detected.

Embodiment 10 FIG.
In the seventh embodiment, the light from the light source 3 is configured to irradiate a plurality of regions of the fingertip portion 1, and the back side of the fingertip portion 1 is brought into contact with the surface 402 orthogonal to the optical axis 400 of the optical system 3. By arranging the optical system 3 so that the tip end side of the fingertip portion of the subject is inclined at a predetermined angle so as to be away from the optical system 3 with respect to the opposite position, the contrast is improved. A fingerprint image can be obtained stably.
However, there is still a part where the peak and valley of the fingerprint cannot be distinguished because the brightness is saturated or the brightness is too low in the range that contains the fingerprint information necessary for personal identification, which is the main part of the fingerprint image. In some cases, the fingerprint image cannot extract information necessary for personal identification.

  Therefore, in the present embodiment, as described in the first embodiment, the brightness of the image is adjusted by adjusting at least one of the light irradiation condition (luminance, irradiation region 16) and the gain of the image pickup means 5 (image pickup device 52). Fingerprints necessary for personal identification, which is the main part of a fingerprint image, by taking multiple fingerprint images of different brightness for the same subject and superimposing or partially pasting these multiple fingerprint images A fingerprint image in which the contrast of light and darkness can be understood with a more appropriate brightness in a range including the information is obtained, and the fingerprint image is more reliably prevented from being deteriorated due to the brightness, thereby obtaining more accurate fingerprint information. The operations for adjusting the brightness of an image and for superimposing or partially pasting a plurality of captured fingerprint images are the same as those described in the first embodiment.

  Also in the fingerprint image imaging apparatus of the eighth embodiment or the ninth embodiment, the brightness of the image is adjusted by adjusting at least one of the light irradiation condition (luminance, irradiation region 16) and the gain of the imaging means 5 (imaging element 52). The plurality of fingerprint images of different brightness for the same subject may be taken, and the plurality of fingerprint images may be superimposed or partially combined to obtain the same effect.

  As described above, according to the present embodiment, the means for adjusting the brightness of the image by adjusting at least one of the light irradiation condition and the gain of the image pickup means 5 (image pickup element 52) (lightness determination unit 66, The light source driving circuit 32 and the gain adjusting circuit 55) and means (image processing unit 62) for superimposing or partially pasting a plurality of fingerprint images having different brightness on the same subject are provided. Can be obtained in a range that includes fingerprint information necessary for personal identification, which is a part, with a more appropriate brightness, and it is more accurate by preventing deterioration of the fingerprint image due to brightness more reliably. Fingerprint information can be obtained.

  In addition, in the fingerprint image imaging devices of Embodiments 7 to 9, the brightness of the image is adjusted by adjusting at least one of the light irradiation condition (luminance, irradiation region 16) and the gain of the imaging means 5 (imaging element 52). As a result, when a fingerprint image with a more appropriate brightness and a contrast of light and darkness is obtained in a range including fingerprint information necessary for personal identification, which is the main part of the fingerprint image, a plurality of lightnesses of the same subject are different. There is no need to superimpose or partially paste the fingerprint images.

Embodiment 11 FIG.
FIG. 32 is a side view showing the overall configuration of the fingerprint image capturing apparatus according to the eleventh embodiment. In the eighth embodiment, the slit light 70 is used for position measurement instead of not providing the subject holding unit 21. However, in the present embodiment, the slit light 70 is also used for finger rest determination. In this case, one or more slit lights 70 are sufficient. The same is true until the position and angle of the fingertip 1 are measured by the finger position measurement unit 67, but the result measured by the finger position measurement unit 67 is within the subject depth of the optical system 4 and the imaging system 5, and If the angle formed by the observation surface 100 and the plane 402 is 10 ° to 30 °, more preferably 15 ° to 25 °, and even more preferably around 20 °, a signal is sent from the finger position measurement unit 67 to the finger stationary determination unit 68. Sent. The finger stationary determination unit 68 compares the positional deviation of the slit light 70 on the reflected light image of the predetermined number of slit lights 70 captured at a predetermined time interval, and the predetermined time until the deviation falls within a predetermined range. A signal is sent to the image capturing unit 61 at intervals, and the image capturing determination is continued. If the deviation is within a predetermined range, it is determined that the subject 1 is stationary. If it is determined that the subject 1 is stationary, a signal is sent to the light source drive circuit 32 to project the light 30 that can pass through the fingertip unit 1, and the light 30 from the light source 3 is set to a predetermined brightness. The light source 3 is turned on by adjusting the number of elements to be lit and the brightness per element. Subsequent operations are the same as those in the eighth embodiment.
In this embodiment, since the image is taken after it is determined that the finger is stationary, it is possible to suppress finger shake and the like.

Embodiment 12 FIG.
FIG. 33 is a side view showing the overall configuration of the fingerprint image capturing apparatus according to the twelfth embodiment. In the eighth embodiment, the position measurement is performed using the slit light 70 instead of providing the subject holding section 21. However, in the present embodiment, the slit light 70 is used to perform the measurement even when the subject holding section 21 exists. Position measurement was performed in the same manner as in Embodiment 8.
As a result, even when the placement of the fingertip 1 on the subject holding unit 21 is not stable, positioning can be performed more precisely.

FIG. 34 is a side view showing the overall configuration of another fingerprint image capturing apparatus according to the twelfth embodiment. In the fingerprint image capturing apparatus shown in FIG. 34, even when the subject holding unit 21 is present, position measurement is performed using the slit light 70, and the slit light 70 is also used for determining finger rest.
Accordingly, even when the placement of the fingertip 1 on the subject holding unit 21 is not stable, it is possible to perform positioning more precisely, and it is determined that the finger is stationary, and then imaging is performed. You can reduce the blurring.

FIG. 35 is a side view showing the overall configuration of still another fingerprint image capturing apparatus according to the twelfth embodiment. In the fingerprint image capturing apparatus shown in FIG. 34, the finger position determination and the finger stationary determination are performed by the slit light 70. However, since the subject holding unit 21 is provided, the position and angle of the fingertip 1 can be easily determined. . In view of this, the fingerprint image pickup apparatus shown in FIG.
As a result, since it is determined that the finger is stationary and the image is taken, blurring of the finger can be suppressed.

  33 to 35, the subject holding unit 21 with an opening having a frame shape is shown as the subject holding unit. However, the angle and position of the fingertip unit 1 can be determined, and the surface of the fingerprint 11 can be determined. Can be used as long as the fingertip part 1 can be held in a non-contact state. For example, as shown in FIG. 26, the outer side of the observation surface 100 is used to hold the ventral tip and the ventral root part of the fingertip part 1. In addition, at least a pair of rod-shaped subject holding parts 22 and the like arranged to face each other with the observation surface 100 interposed therebetween may be used.

  In each of the above embodiments 1 to 12, a marker light source or a slit light source is used for a configuration in which light from the light source 3 can irradiate a plurality of regions of the fingertip portion so as to increase the likelihood of the installation position of the fingertip portion. Although it has been shown that the position and state of the finger can be confirmed, in the case of a device having a marker light source or a slit light source (second light source), the finger tip is used by using the marker light source or the slit light source. It is possible to detect the installation position of the part and reduce the positional deviation of the fingertip part. Therefore, it is not always necessary to apply a plurality of irradiation spots to the fingertip part, and there may be one irradiation region.

  In each of the first to twelfth embodiments, a light source, an imaging unit that captures light from the light source that passes through the subject and obtains a fingerprint image in which the convex portion of the fingerprint is dark and the concave portion is bright, and the subject Compared to a device that includes an optical system that forms an image on the imaging means with light from the light source that passes through, the irradiation position of the light on the fingertip is on the opposite side of the nail from the nail A marker light source or slit for a device that shoots an image by irradiating a portion other than a substantially nail, or a device that shoots an image so that the fingertip portion is inclined at a predetermined angle with respect to the optical axis of the optical system. Although a device having a light source (second light source) is shown, it is not limited to the fingerprint image capturing apparatus having the above-described configuration, and the convex portion of the fingerprint is obtained by imaging light from the light source and the light source that passes through the subject. Imaging means for obtaining a fingerprint image having a dark and bright concave portion, and Irradiate at least one light of a predetermined shape onto the surface of the marker light source or the fingerprint of the subject to an apparatus having an optical system that images the light from the light source that passes through the specimen onto the imaging means By providing the second light source (slit light source), a fingerprint image with good contrast can be stably obtained.

It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 1 of this invention. It is a bottom view which shows a mode that it concerns on Embodiment 1 of this invention and looked at the finger-tip part vicinity from the ventral side. It is a top view which shows a mode that it concerns on Embodiment 1 of this invention and looked at the fingertip part vicinity from the back side. It is a figure which concerns on Embodiment 1 of this invention and shows the fingerprint image imaged by CCD. It is a figure which concerns on Embodiment 1 of this invention and shows the fingerprint image imaged by CCD. It is a figure which concerns on Embodiment 1 of this invention and shows the fingerprint image imaged by CCD. It is a figure which concerns on Embodiment 1 of this invention and shows the fingerprint image imaged by CCD. It is a figure which concerns on Embodiment 1 of this invention and shows the irradiation points AD of the light to the back side of a fingertip part. It is a figure explaining the irradiation area | region concerning Embodiment 1 of this invention. It is a side view which shows another whole structure of the fingerprint image imaging device by Embodiment 1 of this invention. It is a side view which shows another structure of the principal part of the fingerprint image imaging device by Embodiment 1 of this invention. It is a side view which shows another structure of the principal part of the fingerprint image imaging device by Embodiment 1 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 2 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 4 of this invention. It is a bottom view which shows a mode that it concerns on Embodiment 4 of this invention and looked at the fingertip part vicinity from the ventral side. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 5 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 6 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 6 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 6 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 7 of this invention. It is a bottom view which shows a mode that it concerns on Embodiment 7 of this invention and looked at the finger-tip part vicinity from the ventral side. It is a top view which shows a mode that it concerns on Embodiment 7 of this invention and looked at the finger-tip part vicinity from the back side. It is a top view which shows a mode that it concerns on Embodiment 7 of this invention and looked at the finger-tip part vicinity from the back side. 24 is a graph illustrating a relationship between an angle (θ) between a straight line 15 representing the back side of a fingertip portion and a plane 402 orthogonal to the optical axis 300 and the contrast of a fingerprint image according to the seventh embodiment of the present invention. . 24 is a graph illustrating a relationship between an angle (θ) between a straight line 15 representing the back side of a fingertip portion and a plane 402 orthogonal to the optical axis 300 and the contrast of a fingerprint image according to the seventh embodiment of the present invention. . It is a side view which shows another structure of the principal part of the fingerprint image imaging device by Embodiment 7 of this invention. It is a side view which shows another whole structure of the fingerprint image imaging device by Embodiment 7 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 8 of this invention. FIG. 29 is a bottom view showing the vicinity of the fingertip portion as viewed from the ventral side according to the eighth embodiment of the present invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 9 of this invention. FIG. 20 is an enlarged view schematically showing a contact portion between a transparent subject holding portion and a subject according to the ninth embodiment of the present invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 11 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 12 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 12 of this invention. It is a side view which shows the whole structure of the fingerprint image imaging device by Embodiment 12 of this invention.

  DESCRIPTION OF SYMBOLS 1 Fingertip part, 11 Fingerprint, 12 Fingernail, 16 Irradiation area, 2 Subject holding part, 21 Opening subject holding part, 22 Rod-shaped subject holding part, 23 Transparent subject holding part, 3 Light source, 30 Light, 31 Marker light, 32 Light source drive circuit, 33 Marker light source, 4 Optical system, 41 Lens, 42 Aperture, 400 Optical axis, 5 Imaging means, 51 Wavelength selection element, 52 Imaging element, 53 Image output circuit, 55 Gain adjustment circuit, 6 Signal processing unit, 61 Image capture unit, 62 Image processing unit, 63 Fingerprint data storage unit, 64 Personal identification unit, 65 Finger presence determination unit, 66 Lightness determination unit, 67 Finger position measurement unit, 68 Finger rest determination unit, 70 Slit Light, 71 slit light source, 72 slit light source drive circuit, 8 plane mirror.

Claims (4)

A light source that irradiates the subject with light that can pass through the subject, with the fingertip portion having a fingerprint to be imaged as the subject,
A subject holding unit capable of holding the subject in a state where the surface of the fingerprint is not in contact;
An imaging means for imaging the light from the light source that passes through the subject to obtain a fingerprint image in which the convex portion of the internal tissue near the surface of the fingerprint is dark and the concave portion is bright;
An optical system that forms an image on the imaging means of light from the light source that passes through the subject, and the light from the light source irradiates a plurality of regions of the fingertip portion,
And, with reference to the position where the abdomen side of the fingertip part is brought into contact with the subject holding part on a surface orthogonal to the optical axis of the optical system, the tip side of the fingertip part of the subject is compared with the opposite side. A fingerprint image imaging apparatus, wherein the optical system is arranged so as to be inclined at a predetermined angle away from the optical system. 2. The fingerprint image imaging apparatus according to claim 1, further comprising means for adjusting the brightness of the fingerprint image by adjusting at least one of the light irradiation condition and the gain of the imaging means. The fingerprint image capturing apparatus according to claim 2, further comprising means for obtaining a plurality of fingerprint images having different brightness values for the same subject and superimposing or partially pasting the plurality of fingerprint images. The fingerprint processing apparatus according to any one of claims 1 to 3, further comprising a signal processing unit that obtains fingerprint information by performing image processing on the fingerprint image output from the imaging unit and identifies an individual based on the fingerprint information. The fingerprint image pickup device described.

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