JP2008287639A - Optical fingerprint reading apparatus and personal authentication system using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive optical fingerprint reading apparatus capable of acquiring stable and minute images, while further reducing the size in comparison with conventional apparatuses. <P>SOLUTION: In an optical fingerprint reading apparatus that reads a fingerprint image, by irradiating a finger with light from a lighting means and receiving scattered light 12 from inside the finger with a solid-state imaging device 1a, a solid-state imaging device substrate 1 on which the solid-state imaging device 1a is provided and the lighting means are juxtaposed on a wiring board 3. The lighting means, in which a light-emitting device is sealed with a first resin 13, is further sealed with a second resin 14 having lower light transmission than that of the first resin 13, the thickness of the second resin 14 is thinner than that of the first resin 13 in a light irradiation direction from the lighting means to the finger, and is thicker than that of the first resin 13 in any other directions, and unwanted light other than the light irradiating the finger is shielded from the solid-state imaging device 1a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical fingerprint reader that irradiates a finger with light from illumination means and receives scattered light from the inside of the fingertip with a solid-state imaging device, and a personal authentication system using the same.

  In recent years, as economic activities such as electronic commerce spread due to remarkable progress in information technology, the necessity of digitizing personal authentication for the purpose of preventing unauthorized use of information is also increasing. Conventionally, as a method for digitizing personal authentication, a method of acquiring a fingerprint image by a device that reads the fingerprint image and comparing it with a registered image has been widely used.

  An apparatus for reading an image of a fingerprint disclosed in Patent Document 1 or the like irradiates a finger placed on a prism array with light from below through a prism array by light source means, and collects reflected light by a lens. A fingerprint image is picked up by the image pickup means. This apparatus has a problem that it is large in shape and cannot detect forged fingerprints shaped with resin or the like.

  A small-sized and highly reliable fingerprint reading apparatus that improves the above-described points is disclosed in Patent Document 2. This device keeps a finger in contact with the vicinity of the surface of an image sensor having a two-dimensional solid-state image sensor, irradiates the finger with near infrared rays from a light source arranged on the lower side of the finger on the side of the image sensor, It receives scattered light from inside the fingertip.

On the other hand, in order to realize low cost and downsizing, the positions of the fingertip and the solid-state image sensor are relatively moved, and continuous partial images of the moving fingertip are combined into an image of the entire fingertip by image synthesis. A sweeping type device has been proposed (see, for example, Patent Documents 3 and 4). According to this apparatus, since a solid-state image pickup device having a two-dimensional arrangement that has conventionally required an area about the size of a finger only requires the width of the finger, a protective member using a solid-state image pickup device, a fiber optics plate, or the like is provided. It will be cheap. In addition to the optical method described above, this sweep type is also known for reading methods such as a capacitance method and a heat detection method.
JP 2000-11114 A JP 2000-217803 A JP 2002-216116 A JP 2002-133402 A

  However, the above-described conventional apparatus has the following problems when realizing miniaturization and price reduction.

  1) In the case of the optical system, if the illumination unit and the solid-state image sensor are close to each other, the unnecessary light enters the solid-state image sensor, and a stable and clear fingerprint image cannot be obtained. For this reason, there is a limit in bringing the solid-state imaging device and the illumination means close to each other or juxtaposing them, which hinders downsizing required in the market.

  2) Further, there is a risk that the reading surface or the illumination means may be damaged or damaged in the worst case by frequent pressing with a fingertip or a foreign object.

  3) In the method of moving the fingertip, if there are few flat portions, sticking is likely to occur at an irregular speed, and a stable image cannot be obtained.

  With regard to the above problems 1) to 3), sufficient measures have not been taken in the conventional method. Moreover, also in the above-mentioned patent documents 1-4, the description about such a concrete countermeasure is not described at all, or it cannot be said that it is enough. For example, in the apparatus of Patent Document 2, if an image sensor and a light source are brought close to each other, incidence of unnecessary light on a solid-state imaging element is inevitable.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an optical fingerprint reader that can achieve further downsizing and obtain a stable and fine image at a low cost.

  In order to solve the above-described problems, the fingerprint reader of the present invention is an optical fingerprint reader that irradiates a finger with light from illumination means and receives a scattered light from the inside of the finger with a solid-state imaging device to read a fingerprint image of the finger. In the apparatus, the solid-state imaging device substrate on which the solid-state imaging device is disposed and the illuminating unit are juxtaposed on the wiring board, and the illuminating unit in which the light-emitting element is sealed with the first resin is the first illuminating unit. Further sealed with a second resin whose light transmittance is lower than that of the resin, and the thickness of the second resin is thinner than that of the first resin in the light irradiation direction from the illumination means to the finger. In this direction, it is thicker than the first resin, and unnecessary light other than the light applied to the finger is shielded from the solid-state imaging device.

  In the present invention, the solid-state imaging device substrate and the illumination means are juxtaposed on the wiring substrate, and at the same time, unnecessary light is prevented from entering the solid-state imaging device.

  Accordingly, it is possible to provide an optical fingerprint reading apparatus that is smaller than a conventional apparatus and that can obtain a stable and fine image at a low cost.

  Embodiments of a fingerprint reading apparatus according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view showing a fingerprint reading apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view for explaining a sealing resin of the illumination means.

  The fingerprint reading device shown in FIGS. 1 and 2 is of a type (sweep type) that reads a fingerprint image by moving a finger relative to a solid-state imaging device. In the present embodiment, a solid-state imaging device substrate 1 and an infrared / near-infrared LED package 10 as illumination means are juxtaposed on a wiring board 3. By arranging the solid-state imaging device substrate 1 and the LED package 10 close to each other on the same wiring board 3, it is possible to reduce the size and cost.

  A plurality of solid-state image sensors 1 a arranged in a one-dimensional line shape are mounted on the solid-state image sensor substrate 1.

  The solid-state image pickup device substrate 1 is electrically connected to the wiring 3a on the wiring substrate 3 via an Au wire or the like outside the moving region of the finger 20 (for example, both longitudinal end portions in the back direction of the paper) (not shown). .

On the solid-state image pickup device substrate 1, a layered protective member 30 is disposed on the reading surface with which the finger 20 contacts. As a material for the protective member 30, glass, SiO ₂ thin film, SiON thin film, fiber optical plate, or the like can be used. In particular, a silicon substrate is suitable for reducing the price. The silicon substrate can be processed to a desired thickness by back grinding or back lapping. These are bonded onto the solid-state image sensor 1a of the solid-state image sensor substrate 1 with an adhesive that transmits infrared / near infrared.

  In the LED package 10, as described above, the LED chip 10a that emits infrared light and / or near-infrared light, which is a light emitting element, is disposed on the LED substrate 10c, and is electrically connected by the wire 10b. It is sealed with a first resin 13 that transmits the emission wavelength.

  As the first resin 13, an acrylic resin, an epoxy resin, a urethane resin, a silicone resin, a liquid crystal polymer resin, or the like can be used.

  The LED package 10 is mounted on the wiring board 3 using solder or conductive paste.

  In the present invention, in addition to the LED package 10, the same effect can be expected by the following sealing method. That is, the LED chip 10a is directly die-bonded to the wiring board 3 with a conductive paste or the like, electrically connected to the LED chip 10a and the wiring 3a of the wiring board 3 with the wire 10b, and then sealed with the first resin 13. To do.

  The second resin 14 further seals the LED package 10 sealed with the first resin 13, and can be arranged by molding, coating, printing, or the like. In particular, in the method using molding with productivity, the periphery is sealed while the protective member 30 is exposed. For this reason, a method called FAM (Film Assisted Molding) in which a film is sandwiched between the mold and the protective member 30 to absorb the thickness and to ensure releasability is preferable. According to this method, the step on the finger sliding surface between the protective member 30 and the second resin 14 can be set to 100 μm or less. Therefore, the protective member 30 and the second resin 14 can form a continuous surface that can be said to be the same plane that does not inhibit finger sliding.

  The second resin 14 uses a light-shielding resin that covers the side surfaces of the solid-state imaging device substrate 1 and the protection member 30 and cuts at least unnecessary light from the LED chip 10a. As this resin, it is possible to use epoxy, silicone, acrylic resin mixed with pigment / dye and the like.

  In FIG. 2, the second resin 14 has a light transmittance lower than that of the first resin 13, and the thickness A <b> 2 of the second resin 14 in the light irradiation direction to the finger 20 is the thickness of the first resin 13. Thinner than A1. Further, the thickness B2 of the second resin 14 in the other direction in which unnecessary light is desired to be cut is set to be thicker than the first resin thickness B1. Thereby, unnecessary light other than the light irradiated to the finger is absorbed between the resin thicknesses B2, and can be prevented from entering the solid-state imaging device 1a. On the other hand, in the irradiation direction to the finger 20, although absorbed by the second resin 14, the ratio is low because it penetrates depending on the thickness A <b> 2.

  The fingerprint image is read as follows.

  The finger 20 is placed on the surface of the second resin 14 and the protection member 30, and the finger is moved at a right angle to the line of the solid-state imaging device 1a. The surface of the second resin 14 that is the light irradiation surface and the surface of the protective member 30 that is the reading surface are continuous surfaces such as the same plane.

  Light emitted from the LED package 10 becomes incident light 11 on the finger 20, and scattered light 12 from the inside of the finger is received by the solid-state imaging device 1a, and a fingerprint image of the finger 20 is read.

According to this embodiment,
1) Since unnecessary light from the LED chip 10a does not enter the solid-state imaging device 1a, a clearer image can be obtained.

  2) This makes it possible to bring the solid-state imaging device 1a and the LED chip 10a, which is an irradiating means, close to each other.

  3) By covering the LED package 10 with the second resin 14, it is possible to form a continuous surface of the reading surface and the irradiation surface, and it is difficult to cause sticking that causes the fingertip to move at an irregular speed, and is stable. You can get a good picture.

  4) Since the LED package 10 and the solid-state image pickup device substrate 1 are not directly touched by the finger 20, damage or breakage can be prevented.

(Second embodiment)
FIG. 3 is a cross-sectional view showing the fingerprint reading apparatus according to this embodiment, and FIG. 4 is a perspective view thereof.

  The fingerprint reading apparatus shown in FIGS. 3 and 4 has the same overall configuration as that of the first embodiment (see FIGS. 1 and 2), but is a so-called two-dimensionally arranged solid-state imaging device 1a. This is an area-type fingerprint reader.

  In this configuration, by placing the finger 20 on the protective member 30 corresponding to the solid-state imaging device 1a, the finger 20 is stationary without moving, and the image of the fingerprint 20a can be obtained collectively.

  The solid-state imaging device substrate 1 and the wiring substrate 3 are electrically connected by a wire 21 that is an electrical connection portion. The FAM can also be used for sealing and is collectively covered with the second resin 14. As in the first embodiment, a FAM that can be molded while exposing the protective member 30 is applicable.

  In the case of this embodiment, since the solid-state imaging device 1a is rectangular, it is necessary to arrange a plurality of LED packages 10 as illumination means around the solid-state imaging device 1a. This is because it is necessary to illuminate the finger with illumination corresponding to the size and orientation of the finger 20.

Therefore, according to the present embodiment, in addition to the effects of the first embodiment,
1) Since the sealing of the wire 21 can be performed together with covering the LED package 10 with the second resin 14, it is possible to provide a fingerprint reading device that is small in size and low in price.

  2) Since the illumination means can be brought close to the finger 20, it is possible to suppress the illumination distribution (shading) that is likely to occur in the area type, and a more stable and clear fingerprint image can be obtained.

(Third embodiment)
Next, an embodiment of a personal authentication system using the above fingerprint reader will be described with reference to the drawings.

  FIG. 5 is a block diagram showing a configuration of a personal authentication system using a fingerprint reading apparatus according to the third embodiment of the present invention. FIG. 6 is a block diagram showing a configuration of a peripheral circuit unit of the fingerprint reading device.

  The personal authentication system shown in FIG. 5 is connected to the fingerprint reading device 100 having the imaging unit 101 composed of the solid-state imaging device 1a, its peripheral circuit unit 102, and the LED 103 mounted on the LED chip 10, and the fingerprint reading device 100. The fingerprint collation device 200 is provided.

  The peripheral circuit unit 102 shown in FIG. 6 is formed on the above-described solid-state imaging device substrate 1 or the like. The details of the peripheral circuit unit 102 are as follows.

  A control circuit (drive circuit) 1021 controls the operation of the imaging unit 101. The A / D converter 1023 converts an analog imaging signal corresponding to the image relating to the fingerprint of the finger output from the imaging unit 101 from an analog signal to a digital signal via the clamp circuit 1022. The communication control circuit 1024 is a circuit for data communication of the converted digital signal as an image signal of a fingerprint to an external device (such as an interface), and a register 1025 is connected to the communication control circuit 1024. The LED control circuit 1026 controls the light emission of the LED 103. The timing generator 1028 generates a control pulse for controlling the operation timing of the circuits 1021 to 1026 based on the reference pulse supplied from the external oscillator 1027. The circuit including the peripheral circuit unit 102 is not limited to the above, and may include another type of circuit. On the other hand, a part of the circuit may be a separate chip (not shown).

  In the fingerprint collation device 200 shown in FIG. 5, the input interface 111 receives communication data output from the communication control unit of the peripheral circuit unit 102. An image processing unit (fingerprint collation unit) 112 is connected to the input interface 111, and a fingerprint image database (fingerprint registration unit) 113 and an output interface 114 are connected to the image processing unit 112. The output interface 114 is connected to an electronic device (including software) that requires personal authentication in order to ensure security during use or login.

  Here, a fingerprint image of a finger is registered in advance in the fingerprint image database 113 as identification information of a subject to be personally authenticated. The target person here may be one person or multiple persons. The fingerprint image of the target person is input in advance as the personal authentication information of the target person from the fingerprint reading apparatus 100 via the input interface 111 at the time of initial setting or when the target person is added.

  The image processing unit 112 inputs a fingerprint image read by the fingerprint reading device 100 via the input interface 111, and determines whether or not it matches the registered image in the fingerprint image database 113 based on a known fingerprint matching image processing algorithm. To match. The collation result (fingerprint match or mismatch) is output through the output interface 114 as a personal authentication signal.

  In this example, the fingerprint reading apparatus 100 and the fingerprint collation apparatus 200 are configured as separate devices. However, the present invention is not limited to this, and at least a part of the functions of the fingerprint collation apparatus 200 is performed as necessary. The peripheral circuit unit 102 of 100 may be integrated. In addition, the personal authentication system of this example may be configured integrally with an electronic device that requires personal authentication, or may be configured separately from the electronic device.

Sectional drawing which shows the fingerprint reader which concerns on 1st embodiment of this invention. Sectional drawing for demonstrating sealing resin in the illumination means of the fingerprint reader Sectional drawing which shows the fingerprint reader which concerns on 2nd embodiment of this invention. Perspective view showing the same fingerprint reader The block diagram which shows the structure of the personal authentication system using the fingerprint reader which concerns on 3rd embodiment of this invention. Block diagram showing the configuration of the peripheral circuit section of the fingerprint reader

Explanation of symbols

1 ... Solid-state image sensor substrate
1a: Solid-state image sensor
3. Wiring board
3a ... Wiring
4 ... Sealing resin
10 ... LED package
10a ... LED chip
10b ... Wire
10c ... LED substrate
11 ... Incident light
12 ... scattered light
13: First resin
14 ... Second resin
20 ... finger
20a ... fingerprint
21 ... Wire
30 ... Protective member

Claims (10)

In an optical fingerprint reader that irradiates a finger with light from the illumination means, receives scattered light from the inside of the finger with a solid-state imaging device, and reads a fingerprint image of the finger,
The solid-state image sensor substrate on which the solid-state image sensor is disposed and the illumination unit are juxtaposed on a wiring board,
The lighting means in which the light emitting element is sealed with the first resin is further sealed with a second resin having a light transmittance lower than that of the first resin,
The thickness of the second resin is thinner than the first resin in the light irradiation direction from the illumination means to the finger, and thicker than the first resin in the other directions, and is applied to the finger. An optical fingerprint reader characterized in that unnecessary light other than light is shielded against the solid-state image sensor.   2. The optical fingerprint reader according to claim 1, wherein the illuminating means is an LED package sealed with a first resin having LEDs as light emitting elements.   The optical fingerprint reading apparatus according to claim 1, wherein the light emitting element emits infrared light or near infrared light.   4. The optical fingerprint reading apparatus according to claim 1, wherein the solid-state image pickup device substrate is covered with a protective member that comes into contact with a finger.   The optical fingerprint reading apparatus according to claim 4, wherein the second resin covers side surfaces of the solid-state imaging element substrate and the protection member.   6. The optical fingerprint reader according to claim 4, wherein the surface of the second resin and the surface of the protective member form a continuous surface.   The optical fingerprint reader according to any one of claims 1 to 6, wherein the second resin also serves to seal an electrical connection portion between the solid-state imaging device substrate and the wiring substrate. .   The solid-state imaging device is arranged in a plurality of one-dimensional lines, and the fingerprint image is read by moving a finger at right angles to the lines of the solid-state imaging device. An optical fingerprint reader according to claim 1.   The optical fingerprint reading apparatus according to claim 1, wherein a plurality of the solid-state imaging elements are two-dimensionally arranged, and the fingerprint image is read with a finger stationary. Fingerprint registration means for previously registering a fingerprint image of a finger read by the optical fingerprint reading device according to claim 1 as identification information of a subject;
Fingerprint collation means for collating whether or not the fingerprint image of the finger read by the fingerprint reading device matches the registration image of the fingerprint registration means, and outputting the collation result as a personal authentication signal is further provided. A personal authentication system characterized by that.

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