JP4229632B2 - Fingerprint reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fingerprint reader for reading a fingerprint and subjecting it to a predetermined process.
[0002]
[Prior art]
In recent years, so-called biometric personal authentication technology has attracted attention. Among these, fingerprint authentication is expected to be used in many situations because the psychological burden on the authenticated side is small. Conventionally, as a device for reading a fingerprint for fingerprint authentication, there is an apparatus including a transparent triangular prism 1, a light source 2, and a two-dimensional image sensor 3 as shown in FIG. The light wave emitted from the light source 2 (a part thereof) is totally reflected inside the reading surface R of the transparent triangular prism 1 and arrives at the two-dimensional image sensor 3.
[0003]
Here, when the surface of the finger is placed on the reading surface R of the transparent triangular prism 1, the convex portion of the fingerprint is in contact with the reading surface R, and the concave portion is not in contact with the reading surface R ( FIG. 17B). In a general glass material or the like, the portion where the finger is in contact with the reading surface R does not satisfy the total reflection condition, and the light wave is absorbed without being reflected in the portion. For this reason, the image formed by the light wave arriving at the two-dimensional image sensor 3 becomes an image darkened along the convex portion of the fingerprint (FIG. 18).
[0004]
An image read by the two-dimensional image sensor 3 is output to an authentication device (not shown) as electrical image data. The authentication device stores a plurality of fingerprint image data to be authenticated in association with predetermined information, compares each fingerprint image data with input image data, and matches the input image data. If there is fingerprint image data, a predetermined process such as opening and closing a door is executed using information associated with the fingerprint image data.
[0005]
[Problems to be solved by the invention]
However, in the conventional fingerprint reader, the area of the fingerprint reading surface R is small, and the degree of freedom of the finger contact position is low. Therefore, it cannot be applied to the case where the processing is different depending on where the finger is placed, and the usage scene is limited. Therefore, it is sufficient to increase the area of the reading surface. In this case, however, the reading area of the two-dimensional image sensor is increased, and the size of the obtained image data is increased. is there.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fingerprint reading apparatus that can efficiently implement fingerprint reading while enlarging an area where fingerprints can be read.
[0007]
[Means for Solving the Problems]
The present invention for solving the problems of the above conventional example includes a first reflecting surface in which a reflecting surface of light is different between a state in which a finger surface is in contact with a surface and a state in which the finger surface is not in contact with the surface. A waveguide that propagates light waves while alternately reflecting between the first reflecting surface and the second reflecting surface, and a second reflecting surface formed opposite to the first reflecting surface. and a light receiving portion for receiving a light wave passing through the Namitai, propagation path of the light wave in the waveguide body, in the first reflecting surface on which is irradiated by the light wave, the adjacent plurality of read regions to each other is set to, fingerprints of a finger in contact with any of the read area is read by the light receiving unit, further, for each of said plurality of read regions, generates image data based on the image read by the light receiving portion And a small amount of image data corresponding to each reading area. Comprising means for generating synthesized image data synthesized Kutomo two or more, and the synthesized on the basis of image data, characterized that you get the data of the fingerprint image of the finger in contact across the plurality of read regions And Here, the waveguide can be a transparent polyhedron, for example. In this case, the light wave passes through the waveguide while repeating total reflection between the first reflection surface and the second reflection surface. This light wave irradiates a predetermined area of the first reflecting surface, and the irradiated part is defined as a readable area. That is, each region related to the total reflection of a plurality of times becomes a readable region, and fingerprint reading at a plurality of locations is possible .
[0008]
Here, since the path lengths between the respective reading areas and the light receiving units are different from each other, the focus and the size of the read fingerprint image are different for each reading area. Therefore, a means for correcting this may be provided. Examples of such means include one that moves the light receiving section itself, a lens system that corrects an image formed on the light receiving section, and one that selects any of propagation paths having different path lengths.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
[Basic configuration]
A first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the fingerprint reading apparatus according to the present embodiment includes a light emitting unit 11, a waveguide body 12, a light receiving unit 13, and an image processing unit 14. The light emitting unit 11 is an LED (light emitting diode) or the like, and emits light waves. The light wave need not be in the form of a beam like a laser. The waveguide body 12 has a first reflecting surface 21 and a second reflecting surface 22 and a side surface 23 facing each other. Of the side surfaces 23, a surface (incident surface) on the light emitting unit 11 side and a surface on the light receiving unit 13 side. Is cut so that the normal line and the optical axis of the light wave coincide with each other so that the light wave is not totally reflected on the surface. Accordingly, the cross section of the waveguide 12 that is broken along the path of the light wave has a substantially (reverse) trapezoidal shape as shown in FIG. The waveguide 12 is made of glass, for example, and guides the light wave incident between the first reflecting surface 21 and the second reflecting surface 22 to the light receiving unit 13 side while totally reflecting the light wave alternately. At this time, on the first reflecting surface of the waveguide, as shown in FIG. 3, the regions (A to D) irradiated with the light wave are arranged at a certain interval along the path of the light wave. It becomes. Here, when the finger touches any position in the areas A to D of the first reflecting surface 21, a part where the total reflection condition is not satisfied is generated along the convex part of the fingerprint, and the light wave is totally reflected in the part. Moreover, the total reflection condition is satisfied in the concave portion of the fingerprint, and the light wave is totally reflected in the portion. As a result, a light wave reflecting the fingerprint image is guided to the light receiving unit 13. In FIG. 2, light waves that arrive at the light receiving unit 13 among the light waves that satisfy the total reflection condition and are incident at the angles of total reflection by the first reflection surface 21 and the second reflection surface 22 are illustrated.
[0010]
The light receiving unit 13 is a two-dimensional image sensor. The light receiving unit 13 is guided by the waveguide 12 and irradiated with a light wave that has passed through the waveguide 12 to convert an image received on the light receiving surface into an electrical signal and perform image processing. To the unit 14. The image processing unit 14 generates image data from the electrical signal input from the light receiving unit 13 and performs predetermined processing such as collation of the image data.
[0011]
That is, according to the present embodiment, the light wave radiated from the light emitting unit 11 is alternately reflected and guided a plurality of times between the first reflecting surface and the second reflecting surface. When a plurality of areas are irradiated on the reflecting surface, and a finger is placed on any of the irradiated areas, a part of the light waves arrive at the light receiving unit 13 reflecting the image of the fingerprint. In other words, this area is defined as a readable area of the fingerprint image. Thus, according to the present embodiment, the degree of freedom of the finger contact position can be increased, and the usage scene can be expanded.
[0012]
[Size / Focus Correction]
As described above, when the image of the fingerprint is captured regardless of the position of the finger in any of the positions A to D in FIG. 3, the finger is placed at the position D in FIG. 3 that is farthest from the light receiving unit 13, for example. 3 and when the finger is placed at the position C in FIG. 3, the path difference is 2 t / cos θ (where θ is the distance between the first reflecting surface 21 and the second reflecting surface 22). The angle between the normal line of the first reflecting surface 21 and the path of the light wave). Accordingly, if the fingerprint size and the focus are adjusted in accordance with the case where the finger is initially placed at the position D in FIG. 3, when the finger is placed at the position C in FIG. Is preferably separated from the waveguide body 12 by 2 t · n / cos θ along the optical axis (path direction) of the light wave. Here, n is the refractive index of the waveguide 12. Therefore, as shown in FIG. 4, the light receiving unit 13 is housed in the container 31 so that the light receiving unit 13 moves along the optical axis direction, and the container 31 is fixed to the rod 33 driven by the linear actuator 32. Thus, the light receiving unit 13 together with the container 31 is movable in the optical axis direction. In addition to this mechanism, any mechanism that moves the light receiving unit 13 in the linear direction may be used.
[0013]
Fingerprint authentication process It should be noted here that it is not always necessary to know where the finger is actually placed in AD. That is, fingerprint authentication processing (image data matching processing) for image data a to d obtained by moving the light receiving unit 13 assuming that a finger is placed at each of the positions A to D regardless of the actual position. This is because the authentication can be successful if verification is achieved with any of the image data.
[0014]
Correction using an optical system The correction of size and focus not only moves the position of the light receiving unit 13 as described above, but also includes a zoom lens between the waveguide 12 and the light receiving unit 13. Correction can also be realized by providing a (refractive) optical system (lens system) and changing the zoom rate in this optical system.
[0015]
Correction using reflection optical system Further, as shown in FIG. 5, the size / focus correction is performed corresponding to the number of the first movable mirror 41 and the number of readable areas on the first reflection surface 21. A reflecting optical system including a plurality of fixed mirrors 42a, b,... The first movable mirror 41 rotates the reflection surface about a predetermined axis, and guides the light wave that has passed through the waveguide 12 to any one of the plurality of fixed mirrors 42. The second movable mirror 43 is the same as the first movable mirror, and guides the light wave reflected and guided from any one of the fixed mirrors 42 to the light receiving unit 13. The fixed mirrors 42 may be arranged substantially in parallel as shown in FIG. 5, and are arranged so that the total distance (path length) to each of the movable mirrors 41 and 43 is shifted by 2 t · n / cos θ. The
[0016]
Therefore, for example, the rotation angle of the first movable mirror 41 and the second movable mirror 43 is adjusted for each of the A to D in FIG. 3, and when the finger is placed at the position A in FIG. In order to guide the light wave, the path in the reflection optical system is determined such that the light wave is guided through the fixed mirror 42b when placed at the position B in FIG.
[0017]
Correction using image data Further, regarding the correction of the size, the image processing unit 14 may perform the size correction by executing an enlargement / reduction process on the image data by a widely known method.
[0018]
[Multiple light waves]
Up to this point, a case has been described in which there is one light-emitting unit 11 serving as a light source and only one light wave path is provided. However, by providing a plurality of light-emitting units 11 to form a plurality of light waves, FIG. As described above, it is possible to arrange the reading storage areas in a matrix. In this case, a corresponding light receiving unit 13 may be provided for each series of light waves that have passed through the waveguide 12 so that each of the light receiving units 13 receives a fingerprint image. As described above, any series of light waves may be selectively guided to one light receiving unit 13 using the fixed mirror group 51 and the movable mirror 52.
[0019]
Further, by making the two adjacent side surfaces 23 of the side surfaces 23 of the waveguide body 12 light incident surfaces, the readable regions can be arranged concentrically as shown in FIG. In this case, it is also preferable to arrange the movable mirror 55 in the vicinity of the center of the concentric circle and guide the light wave that has passed through the waveguide 12 to the light receiving unit 13 side while being driven to rotate along the angular direction of the concentric circle.
[0020]
Even in these cases, it is preferable to move the light receiving unit 13, use a refractive optical system, use a reflective optical system, or correct image data in order to correct the image size and focus. It is.
[0021]
[Continuous readable area]
Further, as shown in FIG. 9A corresponding to FIG. 2, the light-emitting unit 11 uses a slit or the like so that parallel light beams are incident on the incident surface of the light wave over the entire width in the height direction. By adjusting the light wave, it is possible to generate a continuous readable area in which the readable areas are adjacent to each other. In FIG. 9A, the case where the angle formed by the incident surface and the first reflecting surface 21 is set to 45 degrees is described as an example. However, the angle is not limited to this, and the angle is θ degrees. In this case (in this case, if a light wave is incident along the normal line of the incident surface, the reflection angle becomes θ), as shown in FIG. 9B, 2t in the height direction from the side on the second reflecting surface 22 side. A parallel light beam having a width equal to or larger than x sin θ (where t is a distance between the first reflecting surface 21 and the second reflecting surface 22) may be incident. In this way, the light wave incident from the end on the second reflecting surface 22 side irradiates the first reflecting surface 21 and the light wave incident from the end of the parallel light beam closer to the first reflecting surface 21 When the light is reflected once by the first reflecting surface 21, further reflected by the second reflecting surface 22, and returned to the first reflecting surface 21, the point that irradiates the first reflecting surface 21 coincides (point P). The readable area is continuous. The parallel light beam may be obtained using a refractive optical system and a point light source.
[0022]
In this case, by using a plurality of light waves, the readable area can be arranged in a plane as shown in FIG.
[0023]
Split fingerprint image If the readable area is made continuous in this way, the position where the finger is placed can be given freedom, but if the finger is placed across multiple readable areas, The image may be divided and read. Therefore, the image processing unit 14 generates composite image data obtained by combining at least two pieces of image data corresponding to each reading area, and acquires fingerprint image data based on the combined image data. Specifically, when one series of light waves is used and the finger is placed across the readable areas A and B in FIG. 3, the image data obtained by the image processing unit 14 is shown in FIG. As shown. That is, the fingerprint is divided into left and right at the boundary of the readable area, the left side appears on the right side of the image data, and the right side of the fingerprint appears on the left side of the image data. Therefore, the image processing unit 14 copies and joins the image data to generate composite image data (FIG. 11B).
[0024]
Actually, the size and focus are shifted in the readable areas A and B, so one of the left and right images is slightly blurred. When the correction as described above is performed, for example, each set of Ia and Ib, Ib and Ic, and Ic and Id is set for each of the image data Ia to Id corrected according to each of the four readable areas A to D. Combined composite image data is generated. The composite image data generated in this way is used for processing such as image data collation.
[0025]
This process is the same when a plurality of series of light waves are used. When the area of the readable area covers the area of the finger surface to be read, no matter where the finger is placed, the continuous 2 × 2 readable areas are connected to form composite image data. Is generated, a fingerprint image can be obtained (FIG. 11C). In this case, it is also preferable to perform processing such as image collation after extracting a fingerprint image portion of the composite image data by applying a predetermined image processing technique.
[0026]
[Finger position detection]
If it is detected in which position the finger is placed on the waveguide 12 and this is subjected to the above-described correction processing or the like, more accurate correction and generation of composite image data can be supported. Therefore, as a detection means for detecting the position touched by the finger, for example, as shown in FIG. 12, the detection means is provided on the outer surface of the first reflection surface 21 along the outer periphery over a half circumference, on the surface of the first reflection surface 21. A projector group 61 that projects light in parallel, and a light receiver group 62 that is provided across the outer circumference of the first reflecting surface 21 so as to face the projector group 61 and receives light from each projector. There is. Thereby, the position of the finger is detected based on the position where the light from the projector is blocked.
[0027]
As shown in FIG. 13, a plurality of series of light waves traveling in the first axis (X-axis) direction of the first reflecting surface 21 and the second axis (Y-axis) direction substantially orthogonal to the X-axis direction. When acquiring a fingerprint image in a matrix using a plurality of traveling light waves, information on which of the plurality of light waves in the X-axis direction is a series from which the fingerprint image is obtained and a plurality of light waves in the Y-axis direction The position where the finger touches can also be detected based on information indicating which of the series of light waves is the series from which the fingerprint image is obtained. That is, if the finger is in contact with the readable area P in FIG. 13, a fingerprint image is obtained by the series X1 traveling in the X-axis direction and the series Y1 traveling in the Y-axis direction. A position P to be detected can be detected.
[0028]
Use of detected finger position Information on the finger position thus detected can be applied to correction processing and used for positioning control of the light receiving unit 13 and the like. When generating composite image data, it can be used to determine which readable region image data should be combined.
[0029]
[Combination with display]
In the present embodiment, the first reflecting surface 21 and the second reflecting surface 22 substantially transmit light waves traveling in the normal direction thereof, and therefore the second reflecting surface outside the second reflecting surface 22. If a liquid crystal display, CRT, or the like is arranged toward the side 22, a message or the like can be displayed to the user, and can be applied to applications such as presenting options as shown in FIG.
[0030]
[Configuration using surface light source]
Next, a fingerprint reading apparatus according to the second embodiment of the present invention will be described. As shown in FIG. 15A and FIG. 15B, which is a cross-sectional view taken along line AA of the fingerprint reading device of the present embodiment, the surface light emitting unit 15, the waveguide 12 and the light receiving unit 13 are used. And the image processing unit 14. In addition, about the thing which has the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.
[0031]
The surface light emitting unit 15 is disposed outside the second reflecting surface 22 of the waveguide 12, and a light wave traveling in the normal direction of the second reflecting surface 22 is incident on the waveguide 12 through the second reflecting surface 22. To do. In addition, it is also preferable to stretch the light shielding plate except the surface on the light receiving unit 13 side so that light does not enter from the side surface 23 side. In this case, when a finger contacts the outer surface of the first reflecting surface 21 of the waveguide body 12, as shown in FIG. 16A, scattered light that scatters to the inside of the first reflecting surface 21 is generated at the convex portion of the fingerprint. . In addition, the light wave passes through the first reflecting surface 21 as it is to the concave portion of the fingerprint and proceeds to the outside. In the present embodiment, the scattered light is received to obtain a fingerprint image. That is, as shown in FIG. 16B, a part of the scattered light is guided to the light receiving unit 13 side while being totally reflected between the first and second reflecting surfaces 21 and 22. Since the fingerprint image obtained in this way sees the light waves scattered by the convex portions of the fingerprint, the light and dark state is reversed from that shown in FIG.
[0032]
Here, the number of the surface light emitting portions 15 is not necessarily one. For example, a plurality of surface light emitting units 15 having an area corresponding to the readable area may be arranged. In this case, one of the plurality of surface light emitting units 15 is selectively turned on sequentially so that the finger touches depending on the position of the surface light emitting unit 15 that is turned on when the fingerprint image is obtained by the light receiving unit 13. You can also check the position you are doing. Here, the surface light emitting unit 15 may be a display.
[0033]
Also in the present embodiment, the correction processing in the first embodiment may be performed. Further, when a plurality of surface light emitting units 15 are arranged, a continuous readable area can be defined by adjoining each surface light emitting unit 15, and in this case, the combined image data is generated by connecting the image data. It is also preferable.
[0034]
【The invention's effect】
According to the present invention, by using a small number of light emitting units and light receiving units, a plurality of areas where fingerprints can be read can be provided, and efficient fingerprint reading can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a fingerprint reading apparatus according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a path of a light wave in the fingerprint reading apparatus according to the first embodiment of the invention.
FIG. 3 is an explanatory diagram illustrating a state of a readable area.
FIG. 4 is a diagram illustrating a configuration example for correcting a fingerprint image.
FIG. 5 is a diagram illustrating another configuration example for correcting a fingerprint image.
FIG. 6 is an explanatory diagram showing an outline of a path when a plurality of light waves are arranged.
FIG. 7 is a diagram illustrating a configuration example when a plurality of series of light waves are received by one light receiving unit.
FIG. 8 is an explanatory diagram illustrating another example of a path when a plurality of light waves are arranged.
FIG. 9 is an explanatory diagram showing an incident path of a light wave when a readable region is made continuous.
FIG. 10 is an explanatory diagram showing an outline when a readable region is made continuous.
FIG. 11 is an explanatory diagram illustrating an example of a fingerprint image when a finger is placed across continuous reading areas and an example of obtaining a fingerprint image by combining them.
FIG. 12 is an explanatory diagram illustrating an example of a configuration for detecting a finger position.
FIG. 13 is an explanatory diagram illustrating another example of a configuration for detecting the position of a finger.
FIG. 14 is an explanatory diagram illustrating an example of content displayed on a display.
FIG. 15 is a diagram showing an outline of a fingerprint reading apparatus according to a second embodiment of the present invention.
FIG. 16 is an explanatory diagram showing a path of light waves in a fingerprint reading apparatus according to a second embodiment of the present invention.
FIG. 17 is a diagram illustrating an outline of a conventional fingerprint reader.
FIG. 18 is an explanatory diagram illustrating an example of a general fingerprint image.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transparent triangular prism, 2 Light source, 3 Two-dimensional image sensor, 11 Light emission part, 12 Waveguide, 13 Light receiving part, 14 Image processing part, 15 Surface light emission part, 21 1st reflective surface, 22 2nd reflective surface, 23 Side , 31 container, 32 linear actuator, 33 rod, 35 optical system, 41 first movable mirror, 42 fixed mirror, 43 second movable mirror, 51 fixed mirror group, 52, 55 movable mirror, 61 projector group, 62 light receiver group .

Claims (7)

A first reflecting surface in which the reflection state of light is different between a state in which the finger surface is in contact with the surface and a state in which the finger surface is not in contact; and a second reflecting surface formed opposite to the first reflecting surface; A waveguide that propagates light waves while alternately reflecting between the first reflecting surface and the second reflecting surface;
And a light receiving portion for receiving a light wave passing through the waveguides,
Propagation path of the light wave in the waveguide body, in the first reflecting surface on which is irradiated by the light waves, a plurality of read regions are set to be adjacent to each other, the finger in contact with any of the reading area A fingerprint is read by the light receiving unit, and for each of the plurality of reading areas, at least two of means for generating image data based on an image read by the light receiving unit and image data corresponding to each reading area wherein the means for generating synthetic image data obtained by combining the above, the synthesis based on the image data, read fingerprint features that you get the data of the fingerprint image of the finger in contact across the plurality of read regions apparatus. The fingerprint reader according to claim 1,
The fingerprint reading apparatus further comprising correction means for correcting the read fingerprint image. The fingerprint reader according to claim 2,
The correction means includes
Means for moving the light receiving unit along the optical axis of the light wave, or a lens system provided between the waveguide and the light receiving unit, or propagation of the light wave between the waveguide and the light receiving unit Means for propagating the light wave through any one of a plurality of propagation paths having different propagation path lengths;
Alternatively, the fingerprint reader is at least one of means for generating image data based on an image read by the light receiving unit and correcting the image of the fingerprint by image processing on the image data. The fingerprint reader according to any one of claims 1 to 3,
Means for injecting the light wave so that the light wave propagates through a plurality of paths in the waveguide;
Means for selectively guiding one of the light waves that pass through the waveguide through each of the plurality of paths, provided between the waveguide and the light receiving unit;
The fingerprint reader further comprising: The fingerprint reader according to any one of claims 1 to 4,
Furthermore, on the waveguide, further provided a detection means for detecting the position where the finger contacts,
A fingerprint reading apparatus characterized in that information on a position detected by the detecting means is subjected to a predetermined process . A fingerprint reader according to any one of claims 1 to 5,
The first reflecting surface and the second reflecting surface of the waveguide body are transparent bodies that transmit light incident on each surface from a substantially vertical direction, and the reflection is performed by total reflection on each surface,
A fingerprint reading apparatus comprising display means disposed on the outer surface side of the second reflecting surface so as to be visible from the outside of the first reflecting surface via the waveguide . A fingerprint reader according to any one of claims 1 to 5,
The first reflecting surface and the second reflecting surface of the waveguide body are transparent bodies that transmit light incident on each surface from a substantially vertical direction, and the reflection is performed by total reflection on each surface,
A surface light source disposed on the outer surface side of the second reflecting surface;
Means for limiting the incident angle of the light wave incident on the waveguide;
Have
A fingerprint reading device that reads a fingerprint image of a finger that is in contact with an outer surface of the first reflecting surface when light waves emitted from the surface light source reach the light receiving unit through the waveguide .

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