JP2005018595A - Fingerprint input device, and personal identification system using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a fingerprint input device capable of providing a stable image with fine definition which is smaller than a conventional one. <P>SOLUTION: The fingerprint input device has a solid imaging device 1a whereon a finger 20 of a fingerprint input object person is placed, an LED chip 10 irradiating the finger 20 with light, a solid imaging device substrate 1 arranged with the solid imaging device 1a, and a wiring board 3 arranged with both the solid imaging device substrate 1 and the LED chip 10. A fingerprint image of the finger is read by receiving scattered light 20a from a fingertip interior of the light 10a illuminated on a fingertip from the LED chip 10 by the solid imaging device 1a while relatively moving positions of the fingertip of the finger 10 and the solid imaging device 1a. A protection member 30 is fixed on the solid imaging device substrate 1. The protection member 30 is composed so that a dimension W1 in a moving direction of the relative positions is larger than at least a dimension W2 in a moving direction of the solid imaging device substrate 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fingerprint input device and a personal authentication system using the same, and more particularly, to a finger of light irradiated on the finger from illumination means while relatively moving the position of a finger, more specifically, a fingertip and a solid-state imaging device. More specifically, the present invention relates to a fingerprint input device that receives scattered light from the inside of the fingertip with the solid-state imaging device.
[0002]
[Prior art]
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.
[0003]
Conventionally, as a method for digitizing personal authentication, a method of inputting a fingerprint image has been used in many cases. For example, a device using a total reflection prism described in Patent Document 1 or the like has a large shape and is made of resin or the like. There were difficulties such as being unable to discriminate forged forged fingerprints.
[0004]
As described in Patent Document 2, as a small-sized and highly reliable fingerprint input device that improves such a point, a finger is brought into contact with the vicinity of the surface of the two-dimensional solid-state imaging device, and a near-infrared ray is irradiated. A method for receiving scattered light from inside the fingertip has been proposed. This method will be described with reference to FIG.
[0005]
In the fingerprint input device shown in FIG. 7, solid-state image pickup devices 1 a arranged in a two-dimensional manner at a predetermined interval p are formed on the surface of the solid-state image pickup device substrate 1, and a cover glass 100 is transparent on the sealing material 41. It is fixed with adhesive. The solid-state imaging device substrate 1 is fixed to the wiring substrate 3 and is electrically connected to the wiring 3 a on the wiring substrate 3 by wires 21. Further, the LED 10 chip that emits infrared rays or near infrared rays for illumination is also fixed on the wiring substrate 3, connected to the wiring 3 a on the wiring substrate 3 by the wire 12, and protected by the sealing resin 11. The light beam 10a emitted from the LED chip 10 enters the finger 20, is diffused therein, and enters the cover glass 100 from the fingerprint 20a as scattered light 10b. This incident light reaches the solid-state imaging device 1a through the cover glass 100, where it is photoelectrically converted, whereby an electrical signal of a fingerprint image is obtained.
[0006]
The cover glass 100 has an optical filter function for removing disturbance light other than the fingerprint image at the same time as the purpose of protecting the solid-state imaging device 1a from being touched by the finger 20 or the like and breaking it electrically and mechanically. It is also necessary to make it. However, in order to obtain a clear fingerprint image, the thickness t of the cover glass 100 is required to be extremely thin. To avoid this, an expensive material such as a fiber optics plate (FOP) must be used. There wasn't.
[0007]
On the other hand, as a technique for realizing low cost and downsizing, the position of the fingertip and the solid-state image sensor are relatively moved, and an image of the entire fingertip is obtained by synthesizing a plurality of continuous partial images of the moving fingertip. A sweep type has been proposed (see, for example, Patent Documents 3 and 4). According to this technology, the solid-state image sensor and the fiber optics plate are inexpensive because a two-dimensional array of solid-state image sensors that previously required an area about the size of a finger need only be the width of the finger. In addition to the optical method described above, this sweep type also has input methods such as a capacitance method and a heat detection method.
[0008]
[Patent Document 1]
JP 2000-11142 A [Patent Document 2]
Japanese Patent No. 3150126 [Patent Document 3]
Japanese Patent Laid-Open No. 2002-216116 [Patent Document 4]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-133402
[Problems to be solved by the invention]
However, the above-described conventional method has the following problems when realizing miniaturization and price reduction.
[0010]
1) In the case of the optical system, since the illumination unit and the solid-state image sensor are closer to each other due to miniaturization, unnecessary light enters the solid-state image sensor, and a stable and clear fingerprint image cannot be obtained.
[0011]
2) Since the fingertip is moved, the finger may be injured at the corner of the reading surface in contact with the finger.
[0012]
3) Further, there is a risk that the reading surface or the illumination means may be damaged or worst damaged by frequent pressing with a fingertip or a foreign object.
[0013]
4) Since sufficient sealing is necessary to prevent the sealing material for protecting the electrical connection part such as wire bonding from adhering to the reading surface or flowing out from the desired position. Assemblability is poor, which hinders price reduction.
[0014]
5) Since there are few flat portions, sticking is likely to occur at an irregular speed of fingertip movement, and a stable image cannot be obtained.
[0015]
With respect to the above problems 1) to 5), sufficient measures have not been taken in the conventional method. Also, in the above-mentioned patent publications 1 to 4, such specific explanation about the countermeasure is not described at all or cannot be said to be sufficient.
[0016]
The present invention has been made in view of such problems, and an object of the present invention is to provide a fingerprint input device that is smaller than the conventional one and that can obtain a stable and fine image at low cost.
[0017]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a solid-state image sensor, illumination means for irradiating light on the finger, a solid-state image sensor substrate on which the solid-state image sensor is disposed, the solid-state image sensor substrate, and the illumination means. Are disposed together, and the scattered light from the inside of the finger is irradiated with light emitted from the illuminating means while relatively moving the position of the finger and the solid-state imaging device. In a fingerprint input device that receives light by an imaging device and reads a fingerprint image of the finger, the fingerprint input device has a protective member fixed on the solid-state imaging device substrate, and the protective member has at least a dimension in a moving direction of the relative position. The solid-state imaging device substrate is configured to be larger than the dimension in the moving direction.
[0018]
The protective member may be configured such that the dimension covers the illumination unit together with the solid-state imaging device substrate, and light transmitted through the protective member may be applied to the fingertip.
[0019]
The protective member may have at least two types of regions having different optical characteristics.
[0020]
The present invention may further include a light shielding layer that is disposed between the solid-state imaging device substrate and the illumination unit and shields at least light from the illumination unit. You may provide electroconductivity to this light shielding layer.
[0021]
The protective member may be formed of a silicon substrate having a predetermined thickness. The thickness of the silicon substrate is preferably 30 μm or more and 200 μm or less.
[0022]
The personal authentication system according to the present invention uses any one of the above-described fingerprint input devices. The personal authentication system includes a fingerprint registration unit that pre-registers the fingerprint image of the finger read by the fingerprint input device as identification information of the subject, the fingerprint image of the finger read by the fingerprint input device, and the fingerprint image It is preferable to further comprise fingerprint collation means for collating whether or not the registered image of the fingerprint registration means matches and outputting the collation result as a personal authentication signal.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a fingerprint input device according to the present invention will be described below with reference to the drawings.
[0024]
(First embodiment)
FIG. 1 is a cross-sectional view of the fingerprint input device according to the present embodiment, and FIG. 2 is a perspective view thereof.
[0025]
In the fingerprint input device shown in FIG. 1, a rectangular (rectangular) solid-state imaging device substrate 1 and an LED (Light Emitting Diode) chip 10 are arranged on a wiring substrate 3. A plurality of line-shaped solid-state image pickup devices 1 a are mounted on the solid-state image pickup device substrate 1. The LED chip 10 includes an LED which is an illumination unit that emits infrared light and / or near infrared light.
[0026]
As shown in FIG. 2, the solid-state imaging device substrate 1 is electrically connected to the wiring 3 a on the wiring substrate 3 by a wire 21 at the electrode portion disposed at the end in the longitudinal direction. Similarly, as shown in FIG. 1, the LED chip 10 is also electrically connected to the wiring portion 3 a on the wiring substrate 3 by the wire 12.
[0027]
In the solid-state image pickup device substrate 1, a rectangular protection member 30 is disposed on a reading surface with which a finger 20 of a fingerprint input target person contacts. As shown in FIG. 1, the protective member 30 is set so that the dimension (width dimension) W1 in the finger movement direction (width direction orthogonal to the longitudinal direction) is larger than the dimension W2 of the solid-state imaging device substrate 1. (W1> W2). In particular, in the present embodiment, as shown in FIG. 1, the dimension W1 of the protection member 30 is larger than the dimension W2 of the solid-state imaging element substrate 1 (W1> W2), and the solid-state imaging element substrate is formed on the wiring board 3. 1 is configured to cover the LED chip 10 disposed together with the LED 1 at the same time. Therefore, the dimension W1 of the protection member 30 is obtained by adding the dimension W2 of the solid-state imaging device substrate 1, the size of the distance in the finger movement direction between the solid-state imaging device substrate 1 and the LED chip 10, and the dimension of the LED chip 10 in the finger movement direction. Is set to a value greater than
[0028]
As the material of the protective member 30, glass, a transparent plastic sheet such as polycarbonate, nylon, and acrylic, a fiber optical plate (FOP), or the like can be used. These are bonded on the solid-state image sensor 1a of the solid-state image sensor substrate 1 with an adhesive that transmits infrared / near infrared.
[0029]
In order to read a further low-price and fine image, the protective member 30 1) When light leakage (crosstalk) into the adjacent solid-state imaging device is considered, the light spreads between the incidence and the emission. 2) No refractive light other than illumination light enters to obtain a clear image, 3) Scratch resistance and weather resistance as a protective member, 4) Low cost It is necessary to satisfy the following items: 5) easy workability, 6) warping / deformation, and the linear expansion coefficient is close to that of the solid-state imaging device substrate. A silicon substrate is particularly suitable for satisfying these requirements. The silicon substrate can be processed to a desired thickness by back grinding or back lapping. Further, since infrared and near infrared light is transmitted and visible light is cut, unnecessary light such as outside light can be cut. Since the refractive index is about 3.4, the same resolving power can be obtained even with a thickness 1.5 to 2 times that of glass. When a silicon substrate is used as the protective member 30, a substrate having a thickness of 30 μm to 200 μm can be used. A thickness of 70 to 150 μm is particularly suitable.
[0030]
With the above configuration, the light 10 a emitted from the LED chip 10 passes through the protection member 30 and enters the finger 20. The light diffused inside the finger 20 passes through the protective member 30 again as scattered light 10b and is converted into an electrical signal by the solid-state imaging device 1a.
[0031]
Therefore, according to the present embodiment, the protective member 30 is arranged larger than the solid-state imaging device substrate 1 at least in the finger movement direction, and thus the following effects are obtained.
[0032]
1) While the solid-state image pickup device substrate 1 itself can be made small, a continuous surface can be formed substantially by the protective member 30, so that the finger can move smoothly and image defects due to sticking or the like are reduced. In addition, since there is no step, the finger can easily come into close contact, and a good image can be obtained.
[0033]
2) When the protective member 30 is affixed to the solid-state image sensor substrate 1, if the protective member 30 is affixed after the adhesive resin (sealing resin) 11 is applied to the solid-state image sensor substrate 1 side, the sticking out Since the resin 11 can be bonded without going around the upper surface of the protective member 30, the assemblability in manufacturing is improved. A portion where the adhesive resin 11 is insufficient can be compensated from the surroundings. In this case, the adhesive resin 11 has a function as a sealing resin.
[0034]
3) Since the edge portion of the solid-state imaging device substrate 1 is covered, it is possible to prevent the finger from being damaged at the edge portion. Since the edge portion of the protection member 30 is away from the reading position, there is no hindrance to the read image and the movement of the finger even if it is hidden when incorporated in the main body.
[0035]
According to the above 1) to 3), it is possible to provide a fingerprint input device that is smaller than the conventional one and that can obtain a stable and fine image at low cost.
[0036]
(Second embodiment)
FIG. 3 is a sectional view of the fingerprint input device according to the present embodiment.
[0037]
The fingerprint input device shown in FIG. 3 has the same overall configuration as that of the first embodiment (see FIGS. 1 and 2), but further includes a light shielding layer 40 between the LED chip 10 and the solid-state imaging device substrate 1. The difference is provided. Specific methods include a method of forming a groove with a dicer or a slicer from the protective member 30 side, or a method of filling the groove with a light-shielding resin.
[0038]
According to the present embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.
[0039]
1) Since unnecessary light from the LED chip 10 can be cut by the light shielding layer 40, a more stable and clear image can be obtained.
[0040]
2) In addition, a conductive material such as carbon / silver paste is mixed into the resin filled in the light shielding layer 40, and a conductive means is added to be placed on the ground through the wiring board 3 so as to release static electricity from the finger. The solid-state imaging device 1a and the LED chip 10 can be protected from electrostatic breakdown.
[0041]
(Third embodiment)
FIG. 4 is a sectional view of the fingerprint input device according to the present embodiment.
[0042]
The fingerprint input device shown in FIG. 4 has the same overall configuration as that of the first embodiment (see FIGS. 1 and 2), but further includes a protective member 30 in two optically different regions, that is, a first region 30a. And the second area 30b is different.
[0043]
In the example of FIG. 4, the first region 30 a is configured by, for example, a fiber optical plate (FOP), and is disposed in the central portion of the protection member 30 facing the solid-state imaging device substrate 1. Moreover, the 2nd area | region 30b is comprised, for example with glass, and is arrange | positioned at the both ends which pinch | interpose the 1st area | region 30a of the protection member 30, respectively.
[0044]
With this configuration, it is possible to configure a fiber optical plate that is still expensive even if it is small as a sweep type, so that the following effects can be obtained in addition to the first and second embodiments. Is obtained.
[0045]
1) The protective member 30 can be made inexpensive.
[0046]
2) Even if the incident light 10a from the LED chip 10 passes through the protective member 30, if 10a is selected with a material having a high transmittance, the reduction in the amount of light is slight, so that low power consumption and S / N are ensured. Is possible.
[0047]
(Fourth embodiment)
Next, an embodiment of a personal authentication system using the above-described fingerprint input device will be described with reference to FIGS.
[0048]
The personal authentication system shown in FIG. 5 includes a fingerprint input device 100 having an imaging unit 101 composed of the above-described solid-state imaging device 1a, a peripheral circuit unit 102 thereof, and an LED 103 mounted on the above-described LED chip 10, and this fingerprint input. And a fingerprint collation device 110 connected to the device 100.
[0049]
The peripheral circuit unit 102 is formed on the above-described solid-state imaging device substrate 1 and the like, and is output from the imaging unit 101 and a control circuit (driving circuit) 1021 that controls the operation of the solid-state imaging device 101 as shown in FIG. An A / D converter 1023 that converts an analog image signal corresponding to an image related to a fingerprint of a finger from an analog signal to a digital signal via a clamp circuit 1022, and a digital signal converted by the A / D converter 1023 Are supplied from a communication control circuit 1024 for data communication to an external device (such as an interface) and a register 1025 connected thereto, an LED control circuit 1026 for controlling light emission of the LED 103, and an external oscillator 1027. Control for controlling the operation timing of the circuits 1021 to 1026 based on the reference pulse And a timing generator 1028 for generating a pulse. 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).
[0050]
The fingerprint collation apparatus 110 includes an input interface 111 for inputting communication data output from the communication control unit of the peripheral circuit unit 102, an image processing unit (fingerprint collation unit) 112 connected to the input interface 111, and the image processing. A fingerprint image database (fingerprint registration means) 113 and an output interface 114 connected to the 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.
[0051]
Here, in the fingerprint image database 113, a fingerprint image of the finger of the subject to be personally authenticated is registered in advance. 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 input device 100 via the input interface 111 at the time of initial setting or when the target person is added.
[0052]
The image processing unit 112 inputs a fingerprint image read by the fingerprint input device 100 via the input interface 111, and determines whether or not the image matches the registered image in the fingerprint image database 113 based on a known fingerprint matching image processing algorithm. The collation is performed, and the collation result (fingerprint match or mismatch) is output through the output interface 114 as a personal authentication signal.
[0053]
In this example, the fingerprint input device 100 and the fingerprint collation device 110 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 device 110 is provided 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.
[0054]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a fingerprint input device that is smaller than before and that can obtain a stable and fine image at low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a fingerprint input device according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing a fingerprint input device according to a first embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a fingerprint input device according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a fingerprint input device according to a third embodiment of the present invention.
FIG. 5 is a block diagram showing a configuration of a personal authentication system using a fingerprint input device according to a fourth embodiment of the present invention.
FIG. 6 is a block diagram showing a configuration of a peripheral circuit unit of a fingerprint input device according to a fourth embodiment of the present invention.
FIG. 7 is a cross-sectional view of a conventional fingerprint input device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solid-state image sensor substrate 1a Solid-state image sensor 3 Wiring board 3a Wiring 4 Sealing resin 10 LED chip 10a Incident light 10b Diffuse light 11 Adhesive resin 12 Wire 20 Finger 20a Fingerprint 21 Wire 22 Sealing resin 23 Resin 30 Protective member 30a Area A
30b region B
40 light shielding layer 41 sealing resin 100 cover glass

Claims (8)

A solid-state imaging device, illumination means for irradiating light on a finger, a solid-state imaging device substrate on which the solid-state imaging device is arranged, and a wiring board on which the solid-state imaging device substrate and the illumination means are arranged together, While relatively moving the positions of the finger and the solid-state image sensor, the solid-state image sensor receives scattered light from the inside of the finger of the light irradiated to the finger from the illuminating means, and the fingerprint image of the finger is obtained. In the fingerprint input device to read,
A protective member fixed on the solid-state imaging device substrate;
The fingerprint input device, wherein the protective member is configured such that a dimension of the relative position in the moving direction is at least larger than a dimension of the solid-state imaging device substrate in the moving direction. 2. The fingerprint input according to claim 1, wherein the protective member is configured so that the dimension covers the illumination unit together with the solid-state imaging device substrate, and light transmitted through the protective member is irradiated to the fingertip. apparatus. 3. The fingerprint input device according to claim 1, wherein the protective member has at least two types of regions having different optical characteristics. 4. The fingerprint input according to claim 1, further comprising a light-shielding layer that is disposed between the solid-state imaging device substrate and the illumination unit and shields at least light from the illumination unit. apparatus. 5. The fingerprint input device according to claim 4, wherein conductivity is imparted to the light shielding layer. The fingerprint input device according to claim 1, wherein the protective member is formed of a silicon substrate having a predetermined thickness. A personal authentication system using the fingerprint input device according to claim 1. Fingerprint registration means for registering in advance the fingerprint image of the finger read by the fingerprint input device as identification information of a subject;
Fingerprint collation means for collating whether or not the fingerprint image of the finger read by the fingerprint input device matches the registration image of the fingerprint registration means and outputting the collation result as a personal authentication signal is further provided. The personal authentication system according to claim 7.

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