U.S. patent application number 13/215082 was filed with the patent office on 2011-12-08 for imaging module for biometrics authentication, biometrics authentication apparatus and prism.
Invention is credited to Tsuyoshi MARO, Akito Sakemoto, Akihiko Soya, Takashi Sugiyama, Masaki Yamazaki.
Application Number | 20110298911 13/215082 |
Document ID | / |
Family ID | 39641247 |
Filed Date | 2011-12-08 |
United States Patent
Application |
20110298911 |
Kind Code |
A1 |
MARO; Tsuyoshi ; et
al. |
December 8, 2011 |
IMAGING MODULE FOR BIOMETRICS AUTHENTICATION, BIOMETRICS
AUTHENTICATION APPARATUS AND PRISM
Abstract
An imaging module for biometrics authentication comprises: a
light source irradiating a living body with light capable of
passing through the living body; a prism having an incidence
surface including an incidence area for taking in light emerging
from the living body, two or more reflecting surfaces for
reflecting the light taken in through the incidence area, and an
outlet surface for outputting the light reflected by the reflecting
surfaces; and a camera module including a lens for focusing the
light emerging from the outlet surface of the prism and an image
pickup device for converting the light focused thereon by the lens
into an electric signal and outputting the electric signal.
Inventors: |
MARO; Tsuyoshi; (Ibaraki,
JP) ; Sakemoto; Akito; (Ibaraki, JP) ; Soya;
Akihiko; (Ina, JP) ; Sugiyama; Takashi; (Ina,
JP) ; Yamazaki; Masaki; (Ina, JP) |
Family ID: |
39641247 |
Appl. No.: |
13/215082 |
Filed: |
August 22, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11955114 |
Dec 12, 2007 |
8027519 |
|
|
13215082 |
|
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Current U.S.
Class: |
348/77 ;
348/E7.085 |
Current CPC
Class: |
G06K 9/00046 20130101;
G02B 17/04 20130101 |
Class at
Publication: |
348/77 ;
348/E07.085 |
International
Class: |
H04N 7/18 20060101
H04N007/18 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 13, 2006 |
JP |
2006-336204 |
Apr 19, 2007 |
JP |
2007-110945 |
Apr 19, 2007 |
JP |
2007-110960 |
Apr 19, 2007 |
JP |
2007-111015 |
Claims
1. A biometrics authentication apparatus comprising: a light source
irradiating a living body with light capable of passing through the
living body; a prism wherein the light capable of passing through
the living body to an incidence area included in an incidence
surface of the prism, reflects two or more times inside the prism,
output from an outlet surface of the prism and the incidence area
works as a reflecting surface for the reflection of the light
capable of passing through the living body; a camera module
including a lens for focusing the light emerging from the outlet
surface of the prism and an image pickup device for converting the
light focused thereon by the lens into an electric signal and
outputting the electric signal; and a housing which places the
prism and the camera module at prescribed positions.
2. The biometrics authentication apparatus according to claim 1,
further comprising a finger guide to be used for placing a finger
as the living body at a prescribed position.
3. The biometrics authentication apparatus according to claim 2,
wherein the finger guide has an irradiation window for the
irradiation of the finger with the light emitted by the light
source.
4. The biometrics authentication apparatus according to claim 1,
wherein a light through hole for letting through the light emerging
from the outlet surface of the prism is formed through the
housing.
5. The biometrics authentication apparatus according to claim 4,
wherein the diameter of the light through hole of the housing is
set so that a sufficient amount of light necessary for the imaging
by the camera module passes through the light through hole.
6. The biometrics authentication apparatus according to claim 1,
wherein the housing is formed of material absorbing light from
near-ultraviolet light to near-infrared light.
7. The biometrics authentication apparatus according to claim 1,
wherein at least a surface of the housing facing the prism is
coated with paint absorbing light from near-ultraviolet light to
near-infrared light so that the light emerging from the outlet
surface of the prism will not be reflected by the housing to
reenter the prism as stray light.
8. The biometrics authentication apparatus according to claim 1,
further comprising: a recognition unit which recognizes a blood
vessel pattern of the living body by analyzing the electric signal
output by the image pickup device; a storage unit which has
previously stored blood vessel patterns of living bodies; and an
authentication unit which executes personal authentication by
comparing the blood vessel pattern recognized by the recognition
unit with the blood vessel patterns prestored in the storage
unit.
9. The biometrics authentication apparatus according to claim 1,
wherein the housing has an attachment part to which the camera
module is attached and fixed at a position corresponding to the
outlet surface of the prism; and the light emerging from the outlet
surface of the prism is focused on the image pickup device of the
camera module attached to the housing.
10. The biometrics authentication apparatus according to claim 9,
wherein the attachment part of the housing is a concavity which
engages with a lens tube part containing the lens of the camera
module.
11. The biometrics authentication apparatus according to claim 1,
wherein the light source is placed so that the light is emitted
from the light source in the direction of a normal to the incidence
surface of the prism.
12. The biometrics authentication apparatus according to claim 11,
wherein the light source is placed alongside a surface of the prism
other than the incidence surface, the reflecting surfaces or the
outlet surface.
13. The biometrics authentication apparatus according to claim 11,
wherein a field angle of the light source is set at 45 degrees or
less.
14. The biometrics authentication apparatus according to claim 11,
wherein the light source includes an LED (Light Emitting Diode) and
a condensing lens.
Description
[0001] The present application is a divisional of U.S. application
Ser. No. 11/955,114 filed on Dec. 12, 2007. U.S. application Ser.
No. 11/955,114 claims priority from Japanese applications
JP2006-336204 filed on Dec. 13, 2006, JP2007-110945 filed on Apr.
19, 2007, JP2007-111015 filed on Apr. 19, 2007 and JP2007-110960
filed on Apr. 19, 2007, the entire contents of which are hereby
incorporated by reference into this application.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an imaging module for
biometrics authentication, a biometrics authentication apparatus
and a prism, and in particular, to an imaging module, etc. for
biometrics authentication that are suitable for miniaturization and
low-profiling.
[0003] In recent years, further miniaturization and low-profiling
are commonly requested in applications area of personal devices
such as cellular phones, PCs (Personal Computers) and PDAs
(Personal Digital Assistants).
[0004] Meanwhile, in the field of such personal devices, security
measures against unauthorized use of a device when the device is
lost, stolen, etc. are greatly desired in these years. As one of
the security measures, a technology applying biometrics
authentication (using finger vein patterns, for example) to
personal devices is being highly expected. The authentication using
finger vein patterns is effective as biometrics authentication
since the finger vein pattern differs from individual to
individual. The finger vein authentication technology is especially
advantageous in that the technology, which is generally not
associated by people with criminal investigations differently from
fingerprint authentication, does not cause psychological resistance
and in that counterfeiting a finger vein pattern, not as
information on the surface of a living body (which can be easily
observed from outside) but as characteristics inside a living body,
is difficult.
[0005] The finger vein authentication is performed by use of
near-infrared rays, for example, since near-infrared rays are
absorbed by hemoglobins contained in human blood while
substantially penetrating other parts of a living body. In an image
that is obtained by irradiating a finger (targeted part) of a
person with near-infrared rays from outside and detecting light
emerging from the finger (living body), muscular tissues and bones
in the living body are described as white or bright parts, while
blood vessels absorbing near-infrared rays are described as black
or dark parts. A vein pattern is acquired based on the difference
in the brightness, and the authentication of the person (personal
authentication) is carried out by comparing the acquired vein
pattern with vein patterns that have been registered
previously.
[0006] In order to implement the vein authentication function in
personal devices such as notebook PCs, an imaging module further
miniaturized and low-profiled than conventional imaging modules is
being desired to be developed.
[0007] Under such circumstances, a technique employed in
JP-A-2006-198174 has been widely known as a technique for
miniaturizing an imaging module for finger authentication.
[0008] The technique disclosed in JP-A-2006-198174 acquires
information on a living body (a finger of a person) by irradiating
lateral parts of the finger with near-infrared rays, deflecting the
near-infrared rays emerging from the finger after traveling (being
reflected and dispersed) inside the finger with a reflecting
mirror, converting the deflected rays into an electric signal with
a CCD (Charge-Coupled Device) sensor, and converting the electric
signal into two-dimensional image data with an authentication
unit.
SUMMARY OF THE INVENTION
[0009] However, even such an imaging module for finger
authentication, reflecting (deflecting) the incident light with a
mirror and capturing the reflected light, has not been miniaturized
sufficiently.
[0010] It is therefore the primary object of the present invention
to provide an imaging module for biometrics authentication
realizing the miniaturization and low-profiling.
[0011] In order to achieve the above object, an imaging module for
biometrics authentication in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; and a camera module including a lens for
focusing the light emerging from the outlet surface of the prism
and an image pickup device for converting the light focused thereon
by the lens into an electric signal and outputting the electric
signal.
[0012] Preferably, in the imaging module for biometrics
authentication, the prism is configured so that the light taken in
through the incidence area and reflected by a first reflecting
surface is reflected by the incidence surface including the
incidence area by using the incidence surface also as a second
reflecting surface.
[0013] Preferably, in the imaging module for biometrics
authentication, the prism is configured so that the light taken in
through the incidence area and reflected by the first reflecting
surface is reflected by total reflection in an area of the second
reflecting surface including at least the incidence area.
[0014] Preferably, in the imaging module for biometrics
authentication, an area of the second reflecting surface of the
prism other than the incidence area is coated with a reflective
layer for reflecting the light taken in through the incidence area
and reflected by the first reflecting surface.
[0015] Preferably, in the imaging module for biometrics
authentication, the prism is configured so that the light reflected
by the second reflecting surface is reflected by a third reflecting
surface placed opposite to the second reflecting surface and
thereafter emerges from the prism through the outlet surface.
[0016] Preferably, in the imaging module for biometrics
authentication, the first reflecting surface of the prism includes
a total reflection area which reflects the light taken in through
the incidence area by total reflection and a reflective layer
formation area which reflects the light taken in through the
incidence area by a reflective layer formed on the surface of the
prism. The light source irradiates the living body with the light
capable of passing through the living body via the total reflection
area and the incidence area.
[0017] In order to achieve the above object, an imaging module for
biometrics authentication in accordance with an aspect of the
present invention is configured so that light emerging from a
living body enters a prism through an incidence area of the prism,
reflected inside the prism twice or more, and focused on an image
pickup device. Reflecting surfaces of the prism are placed on
optical paths connecting the incidence area and the image pickup
device.
[0018] Preferably, the imaging module for biometrics authentication
further comprises a filter which blocks visible light.
[0019] Preferably, in the imaging module for biometrics
authentication, a Fresnel lens is formed on the filter.
[0020] In order to achieve the above object, a biometrics
authentication apparatus in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; a camera module including a lens for
focusing the light emerging from the outlet surface of the prism
and an image pickup device for converting the light focused thereon
by the lens into an electric signal and outputting the electric
signal; a recognition unit which recognizes a blood vessel pattern
of the living body by analyzing the electric signal outputted by
the image pickup device; a storage unit which prestores blood
vessel patterns of living bodies; and an authentication unit which
executes personal authentication by comparing the blood vessel
pattern recognized by the recognition unit with the blood vessel
patterns prestored in the storage unit.
[0021] Preferably, the imaging module further comprises a finger
guide to be used for placing a finger as the living body at a
prescribed position.
[0022] Preferably, in the imaging module, the finger guide has an
irradiation window for the irradiation of the finger with the light
emitted by the light source.
[0023] In order to achieve the above object, a prism in accordance
with an aspect of the present invention comprises: an incidence
surface including an incidence area for taking in light emerging
from a living body; a first reflecting surface for reflecting the
light taken in through the incidence surface; a second reflecting
surface for reflecting the light reflected by the first reflecting
surface while serving also as the incidence surface; and an outlet
surface for outputting the light which has been taken in and
reflected. The second reflecting surface includes a total
reflection area which reflects the reflected light from the first
reflecting surface by total reflection.
[0024] Conventional imaging modules for biometrics authentication
further involve the following problem. Even though a conventional
miniaturized and low-profiled imaging module for finger
authentication was designed to prevent unnecessary light from
entering the camera module by use of an optical aperture, the
aperture function against a large amount of unnecessary light has
not necessarily been sufficient due to the miniaturization of the
camera module.
[0025] It is therefore another object of the present invention to
provide an imaging module for biometrics authentication attaining
stable imaging quality by eliminating the unnecessary light.
[0026] In order to achieve the above object, an imaging module for
biometrics authentication in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; a camera module including a lens for
focusing the light emerging from the outlet surface of the prism
and an image pickup device for converting the light focused thereon
by the lens into an electric signal and outputting the electric
signal; and a housing which places the prism and the camera module
at prescribed positions and through which a light through hole for
letting through the light emerging from the outlet surface of the
prism is formed.
[0027] Preferably, in the imaging module for biometrics
authentication, the diameter of the light through hole of the
housing is set so that a sufficient amount of light necessary for
the imaging by the camera module passes through the light through
hole.
[0028] Preferably, in the imaging module for biometrics
authentication, the housing is formed of material absorbing light
from near-ultraviolet light to near-infrared light.
[0029] Preferably, in the imaging module for biometrics
authentication, at least a surface of the housing facing the prism
is coated with paint absorbing light from near-ultraviolet light to
near-infrared light so that the light emerging from the outlet
surface of the prism will not be reflected by the housing to
reenter the prism as stray light.
[0030] In order to achieve the above object, a housing in
accordance with an aspect of the present invention comprises: a
holding part for holding a prism, which takes in light emerging
from a living body and outputs the light, at a prescribed position;
and an attachment part to be used for attaching a camera module,
which converts the light from the prism into an electric signal and
outputs the electric signal, at a prescribed position of the
housing. The attachment part is provided with a light through hole
for letting through the light emerging from the prism and letting
the light enter the camera module.
[0031] In order to achieve the above object, a prism in accordance
with an aspect of the present invention comprises: an incidence
surface including an incidence area for taking in light emerging
from a living body; two or more reflecting surfaces for reflecting
the light taken in through the incidence area; and an outlet
surface for outputting the light which has been reflected by the
reflecting surfaces. A surface other than the incidence surface,
the reflecting surfaces or the outlet surface is painted so as to
absorb light from near-ultraviolet light to near-infrared
light.
[0032] In order to achieve the above object, a biometrics
authentication apparatus in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; a camera module including a lens for
focusing the light emerging from the outlet surface of the prism
and an image pickup device for converting the light focused thereon
by the lens into an electric signal and outputting the electric
signal; a housing which places the prism and the camera module at
prescribed positions and through which a light through hole for
letting through the light emerging from the outlet surface of the
prism is formed; a recognition unit which recognizes a blood vessel
pattern of the living body by analyzing the electric signal
outputted by the image pickup device; a storage unit which
prestores blood vessel patterns of living bodies; and an
authentication unit which executes personal authentication by
comparing the blood vessel pattern recognized by the recognition
unit with the blood vessel patterns prestored in the storage
unit.
[0033] In imaging modules for finger authentication, the
positioning between the prism and the camera module is highly
important since excellent imaging quality can be achieved by an
appropriate positional relationship between the two. However, the
positioning between the prism and the camera module is becoming
more difficult than ever due to the miniaturization and
low-profiling of the imaging modules for finger authentication in
recent years.
[0034] It is therefore another object of the present invention to
provide an imaging module for biometrics authentication realizing
precise positioning between the prism and the camera module and
achieving stable imaging quality with a simple method.
[0035] In order to achieve the above object, an imaging module for
biometrics authentication in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; a camera module including a lens for
focusing the light emerging from the outlet surface of the prism
and an image pickup device for converting the light focused thereon
by the lens into an electric signal and outputting the electric
signal; and a housing holding the prism at a prescribed position
and having an attachment part to which the camera module is
attached and fixed at a position corresponding to the outlet
surface of the prism. The light emerging from the outlet surface of
the prism is focused on the image pickup device of the camera
module attached to the housing.
[0036] Preferably, in the imaging module for biometrics
authentication, the attachment part of the housing is a concavity
which engages with a lens tube part containing the lens of the
camera module.
[0037] Preferably, in the imaging module for biometrics
authentication, the camera module further includes a mount having a
convexity or concavity for the attachment of the camera module to
the attachment part of the housing. The attachment part of the
housing has a concavity or convexity which engages with the
convexity or concavity of the mount.
[0038] In order to achieve the above object, a housing in
accordance with an aspect of the present invention comprises: a
holding part for holding a prism, which takes in light emerging
from a living body and outputs the light, at a prescribed position;
and an attachment part to which a camera module, which converts
light received by its image pickup device into an electric signal
and outputs the electric signal, is attached by engaging the camera
module therewith so as to fix the camera module at a position for
letting the light from the prism focus on the image pickup
device.
[0039] Preferably, in the housing, the attachment part is a
concavity which engages with a lens tube part containing a lens of
the camera module.
[0040] Preferably, in the housing, the attachment part is a
concavity or convexity which engages with a convexity or concavity
formed on a mount of the camera module.
[0041] In order to achieve the above object, a camera module in
accordance with an aspect of the present invention comprises: a
lens for focusing light emerging from a prism taking in light
emerging from a living body; an image pickup device for converting
the light focused thereon by the lens into an electric signal; and
a mount having a convexity or concavity, formed at a prescribed
position relative to the lens and the image pickup device, for
engaging with an attachment part of a housing so as to place the
image pickup device at a position where the light from the prism is
focused by the lens on the image pickup device.
[0042] In order to achieve the above object, a biometrics
authentication apparatus in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; a housing holding the prism at a
prescribed position and having an attachment part; a camera module
which is attached to and engaged with the attachment part of the
housing and which includes a lens for focusing the light emerging
from the outlet surface of the prism in the state with the camera
module attached to the attachment part and an image pickup device
for converting the light focused thereon by the lens into an
electric signal and outputting the electric signal; a recognition
unit which recognizes a blood vessel pattern of the living body by
analyzing the electric signal outputted by the image pickup device;
a storage unit which prestores blood vessel patterns of living
bodies; and an authentication unit which executes personal
authentication by comparing the blood vessel pattern recognized by
the recognition unit with the blood vessel patterns prestored in
the storage unit.
[0043] There is still another problem with conventional imaging
modules for biometrics authentication. Some of the light emitted by
the light source and projected onto the living body is reflected by
the surface of the living body and reenter the imaging module as
unnecessary light. In such cases, the need for eliminating the
unnecessary light makes it difficult to let the camera module
successfully detect the light emerging from the living body after
traveling (being reflected and dispersed) inside the living body.
Further, the amount of light entering the living body decreases
compared to the amount of light irradiating the living body due to
the reflection at the surface of the living body, by which the
amount of the light traveling inside the living body becomes
insufficient.
[0044] It is therefore another object of the present invention to
provide an imaging module for biometrics authentication securing a
sufficient amount of light traveling (being reflected and
dispersed) inside the living body by preventing the reflection at
the surface of the living body.
[0045] In order to achieve the above object, an imaging module for
biometrics authentication in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; a camera module including a lens for
focusing the light emerging from the outlet surface of the prism
and an image pickup device for converting the light focused thereon
by the lens into an electric signal and outputting the electric
signal; and a housing which holds the prism and the camera module
at prescribed positions. The light source is placed so that the
light is emitted from the light source in the direction of a normal
to the incidence surface of the prism.
[0046] Preferably, in the imaging module for biometrics
authentication, the light source is placed alongside a surface of
the prism other than the incidence surface, the reflecting surfaces
or the outlet surface.
[0047] Preferably, in the imaging module for biometrics
authentication, a field angle of the light source is set at 45
degrees or less.
[0048] Preferably, in the imaging module for biometrics
authentication, the light source includes an LED (Light Emitting
Diode) and a condensing lens.
[0049] In order to achieve the above object, a biometrics
authentication apparatus in accordance with an aspect of the
present invention comprises: a light source irradiating a living
body with light capable of passing through the living body; a prism
having an incidence surface including an incidence area for taking
in light emerging from the living body, two or more reflecting
surfaces for reflecting the light taken in through the incidence
area, and an outlet surface for outputting the light reflected by
the reflecting surfaces; a camera module including a lens for
focusing the light emerging from the outlet surface of the prism
and an image pickup device for converting the light focused thereon
by the lens into an electric signal and outputting the electric
signal; a housing which holds the prism and the camera module at
prescribed positions; a recognition unit which recognizes a blood
vessel pattern of the living body by analyzing the electric signal
outputted by the image pickup device; a storage unit which
prestores blood vessel patterns of living bodies; and an
authentication unit which executes personal authentication by
comparing the blood vessel pattern recognized by the recognition
unit with the blood vessel patterns prestored in the storage unit.
The light source is placed at a position outside a spatial domain
formed by extending optical paths connecting the incidence area of
the prism and the image pickup device of the camera module. The
light source is placed so that the light is emitted from the light
source in the direction of a normal to the incidence surface of the
prism.
[0050] By the present invention, an imaging module for biometrics
authentication realizing the miniaturization and low-profiling can
be provided.
[0051] Other objects, features and advantages of the invention will
become apparent from the following description of the embodiments
of the invention taken in conjunction with accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 is an external perspective view of an imaging module
for finger authentication in accordance with a first embodiment of
the present invention.
[0053] FIG. 2 is a cross-sectional view of the imaging module of
the first embodiment.
[0054] FIGS. 3A and 3B are schematic diagrams for explaining
near-infrared irradiation by use of light guides of the imaging
module of the first embodiment.
[0055] FIG. 4 is a schematic diagram for explaining the optical
configuration of the imaging module of the first embodiment.
[0056] FIGS. 5A through 5C are schematic diagrams showing the
optical configurations of imaging modules in accordance with a
second embodiment of the present invention.
[0057] FIG. 6 is a cross-sectional view of another imaging module
in accordance with the second embodiment, in which an LED is placed
behind a first reflecting surface.
[0058] FIG. 7 is a schematic diagram showing another imaging module
in accordance with the second embodiment, which is equipped with
finger guides for regulating the finger.
[0059] FIG. 8 is a schematic diagram showing another imaging module
in accordance with the second embodiment, in which near-infrared
rays are focused on an image pickup device by a wide-angle lens
unit.
[0060] FIG. 9 is an external perspective view of an imaging module
in accordance with a third embodiment of the present invention.
[0061] FIG. 10 is an exploded view of the imaging module of FIG.
9.
[0062] FIGS. 11A and 11B are a top view and a cross-sectional view
of the imaging module of FIG. 9.
[0063] FIGS. 12A and 12B are a top view and a cross-sectional view
of another imaging module in accordance with the third
embodiment.
[0064] FIG. 13 is a block diagram showing the overall composition
of a finger authentication apparatus (equipped with the imaging
module of the first embodiment) in accordance with a fourth
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
[0065] Referring now to the drawings, a description will be given
in detail of preferred embodiments in accordance with the present
invention.
[0066] FIG. 1 is an external perspective view of an imaging module
for finger authentication (hereinafter referred to simply as an
"imaging module 1") as an example of an imaging module for
biometrics authentication in accordance with a first embodiment of
the present invention. FIG. 2 is a cross-sectional view of the
imaging module 1 of the first embodiment.
[0067] As shown in FIGS. 1 and 2, the imaging module 1 includes a
prism 12, a lens unit 13, an image pickup device 14 and a circuit
board 19 which are installed in a housing 10. The housing 10 is
equipped with LEDs (Light-Emitting Diodes) 16 (as an example of
light sources) and light guides 17.
[0068] The housing 10 serves as a cover for surrounding and
protecting the whole imaging module 1. The housing 10 has a window
part 15 formed at a position corresponding to an incidence area 22a
(an area of a surface of the prism 12 (explained later) for taking
in near-infrared rays). A black filter 20 for preventing
reflection, blocking visible light while letting through infrared
light, and protecting the prism 12 is attached to the housing 10 at
the bottom of the window part 15. The housing 10 is equipped with
the light guides 17 having the LEDs 16 as mentioned above. The
housing 10 has irradiation windows 18, through which near-infrared
rays emitted by the LEDs 16 are outputted.
[0069] The window part 15 of the housing 10, corresponding to the
incidence area 22a of the prism 12, is formed to have slanted edges
(see FIG. 3B) so that a finger 50 placed on the window part 15 will
not be deformed to compress veins inside the finger 50. The slanted
edges also serve to prevent the user (subject) from feeling a pain
when the finger 50 enters the window part 15 and contacts the
edges.
[0070] The prism 12 has a substantially rhombic sectional form
(pentagonal form) as shown in FIG. 2. However, the sectional form
of the prism 12 is not restricted to the form shown in FIG. 2.
While an edge of the prism 12 as the boundary between a first
reflecting surface 21 and an incidence surface 22 is chamfered in
the example of FIG. 2, the prism 12 may also be formed to have a
quadrangular sectional form by extending the first reflecting
surface 21 and the incidence surface 22 to let them contact with
each other. As the material of the prism 12, resin or glass that is
transparent to light throughout a wavelength range employed for the
finger vein authentication (visible light-near-infrared light (e.g.
500 nm-1200 nm)) is desirable. The material is desired to have a
high refractive index from the viewpoint of the miniaturization of
the imaging module 1. Resins suitable for the prism 12 include
acryl, cycloolefin polymer, acrylic resin, transparent
fluoroplastic, transparent polyimide, epoxy resin, styrene-based
polymer, polyethylene terephthalate, polypropylene, polyethylene,
silicon resin, polyamide-imide, polyarylate, polysulfone containing
sulfur, polyether sulfone, etc. Resin containing inorganic
particles (e.g. SiO.sub.2, Ta.sub.2O.sub.5) dispersed therein may
also be employed for the prism 12. As the glass material, commonly
used optical glass can be employed.
[0071] On the incidence surface 22 as a surface of the prism 12
facing the window part 15 of the housing 10, an area upon which the
near-infrared rays emerging from the finger 50 are incident (i.e.
an area directly facing the window part 15) will be referred to as
the "incidence area 22a".
[0072] Surfaces of the prism 12 other than the incidence surface 22
will be described later with reference to FIG. 4.
[0073] The lens unit 13 is also formed of resin or glass. The lens
unit 13 condenses the near-infrared rays after being repeatedly
reflected inside the prism 12 (explained later) and thereby focuses
the rays on the image pickup device 14 which will be described
below. The lens unit 13 includes a band-pass filter (unshown) that
selectively lets through near-infrared rays within a specific
narrow band (e.g. 800 nm-1200 nm).
[0074] The image pickup device 14 is implemented by CCD (Charge
Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor),
for example. For the miniaturization and low-profiling of the
imaging module 1, a VGA module of a size not larger than the
1/7-inch type (preferably, not larger than the 1/7.4-inch type) is
desirable. The image pickup device 14 converts the near-infrared
rays (focused on its photoreceiving surface (unshown) by the lens
unit 13) into an electric signal and outputs the generated electric
signal.
[0075] Each LED 16 is implemented by an LED (Light Emitting Diode)
that emits near-infrared rays capable of penetrating a living body.
The LED 16 is suitable as the source of the near-infrared rays
since the LED allows for miniaturization, low power consumption and
low temperature rise. The wavelength of the near-infrared rays
emitted by the LED 16 is desired to be within 800 nm-1000 nm
(preferably, within 850 nm-950 nm).
[0076] Each light guide 17 is formed of resin (e.g. acryl) that
lets through the near-infrared rays emitted by the LED 16. As the
material of the light guide 17, the aforementioned materials
(resin, glass) or various combinations of the materials may be
used.
[0077] FIGS. 3A and 3B are schematic diagrams for explaining the
near-infrared irradiation by use of the light guides 17, wherein
FIG. 3A shows the light guides 17 being attached to the housing
10.
[0078] As shown in FIG. 3A, each LED 16 is placed at an end of a
corresponding light guide 17. Each light guide 17 is attached to
the housing 10 while letting its emitting surface face a
corresponding irradiation window 18 so that the near-infrared rays
from the LED 16 can be outputted through the irradiation window 18.
The near-infrared rays emitted by the LED 16 are reflected by a
curved back surface of the light guide 17, emitted through the
emitting surface of the light guide 17, and outputted to the window
part 15 through the irradiation window 18.
[0079] FIG. 3B is a cross-sectional view for explaining the
arrangement around the window part 15 when the finger 50 is
irradiated with the near-infrared rays.
[0080] As shown in FIG. 3B, the emitting surface of each light
guide 17 is facing obliquely upward, that is, facing the inner part
of the finger 50. Thus, the near-infrared rays emitted through the
emitting surface of the light guide 17 travel toward the inner part
of the finger 50, by which veins within approximately 3 mm of the
skin of the finger 50 can be irradiated with the near-infrared
rays.
[0081] At the irradiation window 18 of the housing 10, a cover of
each light guide 17 on the prism side (lower cover) protrudes from
the emitting surface of the light guide 17, by which the
near-infrared rays emitted from the light guide 17 are prevented
from directly entering the prism 12. Incidentally, while the
circuit board 19 is installed in (attached to) the imaging module 1
of this embodiment as shown in FIG. 2, the circuit board 19 may be
placed outside the imaging module 1 (e.g. installed in a device to
which the imaging module 1 is attached).
[0082] Returning to FIG. 2, electronic parts mounted on the circuit
board 19 include a signal processing unit 25 (see FIG. 13) for
executing signal processing (noise reduction, signal correction,
etc.) to the electric signal outputted by the image pickup device
14 and a recognition unit 26 (see FIG. 13) for recognizing the vein
pattern of the finger 50 (by analyzing the image signal processed
by the signal processing unit 25) and outputting the result of the
vein pattern recognition. The circuit board 19 outputs the vein
pattern (which has been acquired based on the electric signal
outputted by the image pickup device 14) to the outside. The
process will be explained in more detail later referring to a block
diagram of FIG. 13. Incidentally, the electronic parts that should
be mounted on the circuit board 19 are placed outside an area of
the circuit board 19 contacting a third reflecting surface 23 of
the prism 12.
[0083] The optical configuration of the imaging module 1 configured
as above will be described below referring to figures.
[0084] FIG. 4 is a schematic diagram for explaining the optical
configuration of the imaging module 1 of this embodiment.
[0085] The near-infrared rays emitted by the LEDs 16 and outputted
through the light guides 17 and the irradiation windows 18 are
reflected and diffused inside the finger 50, and some of the
near-infrared rays reenter the imaging module 1 through the window
part 15.
[0086] The near-infrared rays entering the prism 12 via the filter
20 and the incidence area 22a (directly facing the window part 15)
of the incidence surface 22 of the prism 12 are first incident upon
the first reflecting surface 21 opposite to the incidence surface
22. The first reflecting surface 21 is coated with a metal
reflective layer by vapor deposition (e.g. aluminum evaporation),
by which the incident near-infrared rays are reflected.
[0087] As shown in FIG. 4, the near-infrared rays after being
reflected by the first reflecting surface 21 return to the
incidence surface 22 including the incidence area 22a. Each
near-infrared ray reflected by the first reflecting surface 21 is
incident upon the incidence surface 22 at a prescribed incident
angle with respect to the direction of the normal to the incidence
surface 22. The incidence surface 22, serving also as a reflecting
surface at this stage, will be referred to also as a "second
reflecting surface 22".
[0088] Differently from the other area of the second reflecting
surface 22, the incidence area 22a is coated with no reflective
layer (e.g. metal evaporation layer) in order to ensure the
transparency to the near-infrared rays. Meanwhile, the other area
of the second reflecting surface 22 (other than the incidence area
22a), which is hidden behind the housing 10, is not required to let
through the near-infrared rays. Further, the incident angle gets
smaller as the distance from the first reflecting surface 21
increases. Thus, the area other than the incidence area 22a is
coated with a reflective layer. As the reflective layer, a metal
reflective layer (Al, Ag, Al alloy, Ag alloy, Cu, Au, etc.), a
reflective layer made up of a stack of transparent dielectric
layers having different refractive indices, etc. can be
employed.
[0089] The near-infrared rays incident upon the incidence area 22a
of the second reflecting surface 22 after being reflected by the
first reflecting surface 21 are totally reflected by the incidence
area 22a (total reflection) according to the relationship between
the refractive index of the prism 12 and the incident angle upon
the second reflecting surface 22. Meanwhile, the near-infrared rays
incident upon the other area of the second reflecting surface 22
(other than the incidence area 22a) are necessarily reflected by
the reflective layer even when the incident angle in the area does
not satisfy the condition for the total reflection. The
near-infrared rays reflected by the second reflecting surface 22 as
above travel toward the third reflecting surface 23 opposite to the
second reflecting surface 22.
[0090] The third reflecting surface 23 is coated with a metal
reflective layer similarly to the first reflecting surface 21, by
which the incident near-infrared rays are reflected and deflected
toward an outlet surface 24 of the prism 12. The near-infrared rays
travel perpendicularly to the outlet surface 24, penetrate the
outlet surface 24, and thereafter travel toward the lens unit 13.
The near-infrared rays are condensed by the lens unit 13 to focus
on the image pickup device 14. Incidentally, while the outlet
surface 24 in this embodiment is not coated with a reflective
layer, an area of the outlet surface 24 not for letting through the
near-infrared rays may be coated with a reflective layer so as to
prevent unnecessary light from entering the prism 12.
[0091] Surfaces of the prism 12 other than the incidence surface 22
(second reflecting surface 22), the first reflecting surface 21,
the third reflecting surface 23 or the outlet surface 24
(hereinafter referred to as "lateral surfaces") are coated with
paint so that light from the near-ultraviolet region to the
near-infrared region are absorbed by the coating. The lateral
surfaces are desired to be painted so as to absorb light from the
near-ultraviolet region to the near-infrared region, for example.
Specifically, the coating (paint) on the lateral surfaces is
desired to absorb wavelength components of light that are used for
the biometrics authentication (finger authentication). In this
embodiment, a coating absorbing light from the visible region to
the near-infrared region is desirable since the LEDs 16 emitting
near-infrared light or visible light are employed as the light
sources.
[0092] Inside the finger 50, living tissues having transparency to
near-infrared rays (e.g. muscular tissues and bones) let through or
disperse the near-infrared rays. On the other hand, blood vessels
(containing blood having hemoglobins, etc. absorbing near-infrared
rays) absorb the near-infrared rays. Therefore, in the image
focused on the image pickup device 14, the blood vessels are
described as dark parts while the other tissues are described as
bright parts. The image pickup device 14 converts the focused image
into an electric signal and outputs the obtained electric signal to
the circuit board 19.
[0093] As described above, in the imaging module 1 in accordance
with the first embodiment of the present invention, the prism 12 is
formed to have two or more reflecting surfaces and the
near-infrared rays entering the prism 12 are reflected twice or
more inside the prism 12. Since the arrangement of the two or more
reflecting surfaces is strictly determined by the shape of the
prism 12, the arrangement of the reflecting surfaces can be set
more precisely within a smaller size compared to cases where the
near-infrared rays are reflected by use of two or more mirrors.
With this configuration, the miniaturization and low-profiling of
the imaging module 1 is realized. Basically, on each reflecting
surface, an area incapable of total reflection due to the
relationship with the incident angle is coated with a reflective
layer.
[0094] By this embodiment, a low-profile imaging module 1 can be
realized since a long optical path can be folded twice or more and
arranged inside a thin prism 12 installed in the imaging module 1.
In the first embodiment (in which the distance between an edge of
the window part 15 and the back of the image pickup device 14 is
approximately 25 mm), the folding of the long optical path was
attained by a prism 12 as thin as 5 mm when the angle between the
incidence surface 22 and the first reflecting surface 21 was 25
degrees and the supplement of the angle between the incidence
surface 22 and the outlet surface 24 was 50 degrees as shown in
FIG. 4.
[0095] With the imaging module 1 of this embodiment, the thickness
of the module (including the housing 10 and the circuit board 19)
was successfully reduced to less than 10 mm (when the size of the
window part 15 was approximately 20 mm.times.20 mm) while also
realizing low optical distortion (0.7% that is .ltoreq.2%). At the
position of a vein of the finger 50, a great depth of field
(.gtoreq.1 mm) and a high resolution (30 .mu.m) were achieved.
[0096] The folding and arrangement of the long optical path inside
the prism 12 is realized in this embodiment by the use of the
incidence surface 22 (including the incidence area 22a having
transparency to the near-infrared rays) also as the second
reflecting surface 22.
[0097] Further, since the incidence area 22a of the second
reflecting surface 22 is designed to totally reflect the
near-infrared rays incident from the inside of the prism 12, the
incidence area 22a can also be used as a reflecting surface (second
reflecting surface 22) while ensuring its transparency to the
near-infrared rays entering the prism 12 from outside.
[0098] Furthermore, the reflection of the near-infrared rays by the
second reflecting surface 22 including the incidence area 22a is
secured by forming the reflective layer on the area of the second
reflecting surface 22 (having the incidence area 22a) in which
total reflection is originally unavailable.
Embodiment 2
[0099] FIGS. 5A through 8 are schematic diagrams showing imaging
modules in accordance with a second embodiment of the present
invention.
[0100] The imaging module 1 shown in FIG. 5A differs from that in
the first embodiment (see FIG. 4) in that the near-infrared rays
are reflected four times inside the prism 12.
[0101] The distance (optical path) from the incidence area 22a to
the back of the image pickup device 14 is folded up and arranged
inside the prism 12 (approximately 5 mm thick) by three reflections
in the imaging module 1 of FIG. 4, whereas the folding of the
optical path is implemented by four reflections in the example
shown in FIG. 5A (first example).
[0102] The imaging module 1 shown in FIG. 5B differs from that in
the first embodiment (FIG. 4) in that the third reflecting surface
23 is placed closer to the second reflecting surface 22. In the
example shown in FIG. 5B (second example), the optical path is
folded up and arranged inside a prism 12 (approximately 5 mm thick)
by three reflections.
[0103] The imaging module 1 shown in FIG. 5C differs from that in
the first embodiment (FIG. 4) in that the near-infrared rays are
reflected twice inside the prism 12. In the example shown in FIG.
5C (third example), the optical path is folded up and arranged
inside a prism 12 that is approximately 6 mm thick by two
reflections.
[0104] FIG. 6 is a cross-sectional view of another imaging module
30 in accordance with the second embodiment, in which an LED 16 is
placed behind the first reflecting surface 21 of the imaging module
1 of the first embodiment (FIG. 2).
[0105] In the imaging module 30 of FIG. 6, an area of the first
reflecting surface 21 capable of total reflection is not coated
with a metal reflective layer so that the near-infrared rays
emitted by the LED 16 can pass through the first reflecting surface
21. The reflective layer is formed by vapor deposition only in the
other area of the first reflecting surface 21 in which total
reflection is impossible. Specifically, an area of the first
reflecting surface 21 in the vicinity of the incidence area 22a is
the total reflection area where no reflective layer (by vapor
deposition) is formed. In the imaging module 1 of the first
embodiment (FIG. 2) in which the finger 50 is irradiated with
near-infrared rays from right and left sides, the light amount of
near-infrared rays can be insufficient around the center line of
the finger 50. On the other hand, the imaging module 30 of FIG. 6
almost squarely irradiating the finger 50 with near-infrared rays
can eliminate the problem (insufficient light amount around the
center line of the finger 50).
[0106] FIG. 7 is a schematic diagram showing another imaging module
40 in accordance with the second embodiment, which is equipped with
finger guides 27 for regulating lateral parts of the finger 50 and
a finger guide 27a for regulating the tip of the finger 50.
Although the finger guide 27a is not necessarily essential, the
finger 50 can be regulated more precisely and the accuracy of the
vein pattern recognition can be increased by use of the finger
guide 27a.
[0107] The imaging module 40 of FIG. 7 helps the user (subject) to
intuitively recognize where to place his/her finger 50, as well as
blocking external light from entering the finger 50 at low angles.
Further, by providing the finger guides 27 with irradiation windows
18 as shown in FIG. 7, veins that should be scanned and imaged
(veins within a prescribed depth (e.g. approximately 3 mm) of the
skin of the finger 50) can be irradiated with near-infrared rays
more efficiently and the whole finger 50 can be irradiated more
evenly in comparison with the imaging module 1 of the first
embodiment (see FIGS. 1 and 2).
[0108] FIG. 8 is a schematic diagram showing another imaging module
in accordance with the second embodiment, in which the
near-infrared rays are focused on the image pickup device 14 by a
wide-angle lens unit 28 only, without using the prism. The imaging
module of FIG. 8, as an example of low-profiling without using a
prism, has an advantage of a wide angle of view. Also with this
configuration, the thickness of the whole imaging module was
reduced to less than 7 mm.
[0109] Further, it is also possible to configure a telecentric
optical system (unshown) by forming a Fresnel lens on the top
surface (facing the finger 50) of the filter 20 shown in FIG. 2. By
letting the near-infrared rays enter the prism 12 as substantially
parallel rays, changes in the size of the image (vein pattern) can
be kept to a minimum even if the object (finger 50) moved up and
down, by which the image processing can be simplified. While the
Fresnel lens unit can not be formed on the surface of the prism 12
facing the window part 15 (since the surface has to be used also as
a total reflection surface), the Fresnel lens unit can be formed on
the filter 20, without hindering the total reflection inside the
prism 12.
[0110] Incidentally, while all the reflecting surfaces of the prism
12 are formed as plane surfaces in the above embodiments, some of
the reflecting surfaces may be formed as curved surfaces (unshown).
Such a configuration makes it possible to leave out the lens unit
13 and further miniaturize the imaging module.
Embodiment 3
[0111] FIGS. 9 through 12 are schematic diagram showing imaging
modules in accordance with a third embodiment of the present
invention.
[0112] In an imaging module 30 shown in FIGS. 9 through 11B, the
prism 12 and a camera module 33 are held by a housing 31. On
lateral faces of the housing 31, LEDs 34a-34f (as an example of
light sources) are placed.
[0113] The housing 31 is formed of resin (e.g. black polycarbonate)
by molding. The housing 31 holds the prism 12 in its holding part
31a as shown in FIG. 11B. A concavity (to which the camera module
33 is attached) is formed in an attachment part 31b of the housing
31 facing the outlet surface 24 of the prism 12. The housing 31 is
desired to be made of material absorbing light from the
near-ultraviolet region to the near-infrared region, for example.
Specifically, materials absorbing wavelength components of light
used for the biometrics authentication (finger authentication) are
desirable for the housing 31. In this embodiment, materials
absorbing light from the visible region to the near-infrared region
are desirable since the LEDs 34a-34f emitting near-infrared light
or visible light are employed as the light sources.
[0114] Incidentally, the inner surface (facing the prism 12) of the
holding part 31a for holding the prism 12 may be painted so that
the rays emerging from the outlet surface 24 of the prism 12 will
not be reflected by the housing 31 to reenter the prism 12 as stray
light (unnecessary light). Also in this case where the housing 31
is painted, the paint is desired to absorb light from the
near-ultraviolet region to the near-infrared region, for example.
Specifically, the paint is desired to absorb wavelength components
of light that are used for the biometrics authentication (finger
authentication). In this embodiment, paint absorbing light from the
visible region to the near-infrared region is desirable since the
LEDs 34a-34f emitting near-infrared light or visible light are
employed as the light sources.
[0115] By fitting the prism 12 in the holding part 31a of the
housing 31, the prism 12 is held at a prescribed position in the
housing 31. The positioning between the prism 12 and the camera
module 33 is completed by attaching the camera module 33 to the
concavity of the attachment part 31b of the housing 31.
[0116] The attachment part 31b of the housing 31 has a circular
light through hole 32 for letting through light. The light through
hole 32, formed to be concentric with the concavity of the
attachment part 31b, lets through the rays emerging from the outlet
surface 24 of the prism 12 and lets the rays enter the camera
module 33. The diameter of the light through hole 32 is set
suitably so that a sufficient amount of light (necessary for the
imaging by the camera module 33) passes through the light through
hole 32, by which stray light (unnecessary light) entering the
camera module 33 from the prism 12 is reduced. Specifically, in
cases where the optical system of the camera module 33 has a front
aperture configuration, setting the diameter of the light through
hole 32 at that of the front aperture required for the imaging
makes it possible to let the light through hole 32 reduce the
amount of rays (emerging from the outlet surface 24) to that
necessary for the imaging. With this configuration, the front
aperture can be left out from the camera module 33. When the camera
module 33 is equipped with a front aperture (unshown), an aperture
adjustment function of the camera module 33 is made possible by
setting the diameter of the light through hole 32 larger than the
maximum diameter of the front aperture.
[0117] The LEDs 34a-34f, having the same performance as the LEDs 16
shown in FIG. 2, are implemented by light-emitting diodes emitting
near-infrared light or visible light capable of penetrating a
living body. The LEDs 34a-34f are placed at positions outside a
spatial domain formed by extending the optical paths (unshown)
connecting the incidence area 22a (see FIG. 2) of the prism 12 and
the image pickup device 14 (see FIG. 2) of the camera module 33.
For example, the LEDs 34a-34f are placed alongside the lateral
surfaces of the prism 12 (other than the incidence surface 22, the
first reflecting surface 21, the third reflecting surface 23 or the
outlet surface 24 shown in FIG. 2) as shown in FIG. 9.
[0118] The LEDs 34a-34f are desired to have high directivity. For
example, the field angle (half-value total angle: angular range
within which light emission intensity is half the peak value
(center value) or more) of each LED 34a-34f is desired to be 45
degrees or less. Preferably, the field angle is set at 30 degrees
or less. However, even LEDs having low directivity can be used for
the LEDs 34a-34f, by combining the LEDs with condensing lenses.
[0119] The LEDs 34a-34f emit rays in the direction of the normal to
the incidence surface 22 of the prism 12. Therefore, the rays
emitted by the LEDs 34a-34f are incident upon the living body
(finger 50) substantially at right angles, by which reflection of
the rays at the surface of the living body can be reduced.
Incidentally, it is possible to further employ light guide tubes
(unshown) in order to project the rays onto the living body
substantially at right angles. The use of the light guide tubes can
relax restrictions on the arrangement of the LEDs.
[0120] FIGS. 12A and 12B are a top view and a cross-sectional view
of another imaging module 40 in accordance with the third
embodiment. Also in this imaging module 40, the prism 12 and a
camera module 43 are held by a housing 41. The imaging module 40 of
FIGS. 12A and 12B differs from the imaging module 30 of FIGS. 11A
and 11B (in which the camera module 33 is fitted into and fixed to
the concavity formed in the attachment part 31b of the housing 31)
in that the camera module 43 is attached and fixed to the housing
41 by fitting convexities 43b formed on a mount 43a of the camera
module 43 into concavities 41c formed in an attachment part 41b of
the housing 41.
[0121] The housing 41 holds the prism 12 in its holding part 41a as
shown in FIG. 12B. Two or more concavities 41c are formed in the
attachment part 41b of the housing 41 in order to firmly fix the
camera module 43 at a prescribed position. A light through hole 42
for letting through light is formed through the attachment part 41b
of the housing 41 similarly to the light through hole 32 shown in
FIG. 11B.
Embodiment 4
[0122] In the following, a finger authentication apparatus 100
equipped with the aforementioned imaging module 1 will be described
referring to FIG. 13. While the imaging module 1 described in the
first embodiment is employed for the finger authentication
apparatus 100 in this embodiment, the finger authentication
apparatus 100 may also be implemented with other imaging modules
described in the previous embodiments.
[0123] FIG. 13 is a block diagram showing the overall composition
of the finger authentication apparatus 100 as an example of a
biometrics authentication apparatus in accordance with a fourth
embodiment of the present invention. The finger authentication
apparatus 100 can be used for the personal authentication of users
of a personal device such as a notebook PC.
[0124] As shown in FIG. 13, the finger authentication apparatus 100
of this embodiment includes the imaging module 1, a storage unit 51
which prestores vein patterns, and an authentication unit 52 which
executes the personal authentication by comparing a vein pattern
recognized by the recognition unit 26 (explained later) with the
vein patterns prestored in the storage unit 51. The imaging module
1 includes LEDs 16 for emitting near-infrared rays for the
irradiation of the finger 50 of the user (subject), the image
pickup device 14 for capturing the near-infrared rays emerging from
the finger 50, the signal processing unit 25 for executing signal
processing to the electric signal outputted by the image pickup
device 14, and the recognition unit 26 for recognizing the vein
pattern of the finger 50 based on the image signal processed by the
signal processing unit 25.
[0125] The signal processing unit 25, connected to the image pickup
device 14 and the recognition unit 26, executes the signal
processing (noise reduction, signal correction, etc.) to the
electric signal outputted by the image pickup device 14 and
supplies the result of the signal processing (image signal) to the
recognition unit 26.
[0126] The recognition unit 26 recognizes the vein pattern of the
finger 50 by analyzing the image signal processed by the signal
processing unit 25 and outputs the recognized vein pattern to the
authentication unit 52.
[0127] The storage unit 51 is connected to the authentication unit
52. The storage unit 51, prestoring a plurality of vein patterns
previously captured by the imaging module 1, supplies the stored
vein patterns to the authentication unit 52 in response to
instructions from the authentication unit 52 which will be
explained below. When a vein pattern of a finger 50 of a person is
newly captured and recognized by the recognition unit 26 of the
imaging module 1, the storage unit 51 acquires the new vein pattern
from the recognition unit 26 and stores the vein pattern therein
while associating it with personal information on the person.
[0128] The authentication unit 52 is connected to the recognition
unit 26 and the storage unit 51. The authentication unit 52
executes the personal authentication by comparing the vein pattern
of the finger 50 captured and recognized by the imaging module 1
with the vein patterns prestored in the storage unit 51.
[0129] Next, the biometrics authentication method carried out by
the finger authentication apparatus 100 will be described
below.
[0130] After the finger 50 of a user (subject) is placed on the
imaging module 1, the finger 50 is irradiated with the
near-infrared rays emitted by the LEDs 16. Some of the
near-infrared rays entering and being dispersed inside the finger
50 enter the prism 12 of the imaging module 1 via the window part
15.
[0131] The near-infrared rays entering the prism 12 are reflected
inside the prism 12 and thereafter focused on the image pickup
device 14 via the outlet surface 24 and the lens unit 13. The image
pickup device 14 generates the electric signal based on the image
focused thereon and outputs the electric signal to the circuit
board 19.
[0132] On the circuit board 19 receiving the electric signal, the
signal processing unit 25 generates the image signal by executing
noise reduction, signal correction, etc. to the electric signal.
Subsequently, the recognition unit 26 on the circuit board 19
recognizes (generates) the vein pattern inside the finger 50 based
on the image signal generated by the signal processing unit 25 and
outputs the generated vein pattern to the authentication unit 52
connected to the imaging module 1. The vein pattern inside the
finger 50 is captured and outputted by the imaging module 1 as
above.
[0133] The authentication unit 52 acquiring the vein pattern from
the imaging module 1 executes the personal authentication by
comparing the acquired vein pattern with the vein patterns
prestored in the storage unit 51. The biometrics authentication is
carried out by the finger authentication apparatus 100 as
above.
[0134] As described above, the finger authentication apparatus 100
of this embodiment carries out the personal authentication based on
the vein pattern which is outputted by the sufficiently
miniaturized and low-profiled imaging module 1. Therefore, the
miniaturization and low-profiling of the finger authentication
apparatus 100 can be realized.
[0135] Incidentally, while the present invention has been applied
to finger authentication (using a vein pattern of a finger 50) in
the above embodiments as an example of biometrics authentication,
the present invention is also applicable to other types of
biometrics authentication such as palm authentication, forehead
blood vessel authentication, etc.
[0136] It should be further understood by those skilled in the art
that although the foregoing description has been on embodiments of
the invention, the invention is not limited thereto and various
changes and modifications may be made without departing from the
spirit of the invention and the scope of the appended claims.
* * * * *