U.S. patent application number 14/254339 was filed with the patent office on 2014-08-14 for biological information detector and biological information measurement device.
This patent application is currently assigned to SEIKO EPSON CORPORATION. The applicant listed for this patent is SEIKO EPSON CORPORATION. Invention is credited to Yoshitaka IIJIMA, Shigemi SATO, Hideto YAMASHITA.
Application Number | 20140228690 14/254339 |
Document ID | / |
Family ID | 43836655 |
Filed Date | 2014-08-14 |
United States Patent
Application |
20140228690 |
Kind Code |
A1 |
SATO; Shigemi ; et
al. |
August 14, 2014 |
BIOLOGICAL INFORMATION DETECTOR AND BIOLOGICAL INFORMATION
MEASUREMENT DEVICE
Abstract
A biological information detector includes a light-emitting
part, a reflecting part, and a light-receiving part. The
light-emitting part is configured and arranged to emit light
directed at a detection site of a test subject. The reflecting part
is arranged at the periphery of the light-emitting part. The
light-receiving part is configured and arranged to receive
reflected light at the detection site including biological
information. The light-emitting part and the light-receiving part
are arranged not to overlap each other in plan view. A distance
between the detection site and the light-emitting part is different
from a distance between the detection site and the light-receiving
part.
Inventors: |
SATO; Shigemi; (Asahi-mura,
JP) ; IIJIMA; Yoshitaka; (Shiojiri, JP) ;
YAMASHITA; Hideto; (Suwa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEIKO EPSON CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
SEIKO EPSON CORPORATION
Tokyo
JP
|
Family ID: |
43836655 |
Appl. No.: |
14/254339 |
Filed: |
April 16, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12973313 |
Dec 20, 2010 |
8740791 |
|
|
14254339 |
|
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Current U.S.
Class: |
600/479 |
Current CPC
Class: |
A61B 5/02427 20130101;
A61B 2562/0233 20130101; A61B 5/14552 20130101; A61B 5/7203
20130101; A61B 5/6824 20130101; A61B 2562/043 20130101 |
Class at
Publication: |
600/479 |
International
Class: |
A61B 5/024 20060101
A61B005/024; A61B 5/00 20060101 A61B005/00; A61B 5/1455 20060101
A61B005/1455 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 5, 2010 |
JP |
2010-000451 |
Claims
1. A biological information detector comprising: a light-emitting
part configured and arranged to emit light directed at a detection
site of a test subject; a reflecting part arranged at the periphery
of the light-emitting part; and a light-receiving part configured
and arranged to receive reflected light at the detection site
including biological information, wherein the light-emitting part
and the light-receiving part are arranged not to overlap each other
in plan view, and a distance between the detection site and the
light-emitting part is different from a distance between the
detection site and the light-receiving part.
2. The biological information detector according to claim 1,
wherein the reflecting part includes a first reflecting part which
surrounds the light-emitting part.
3. The biological information detector according to claim 1,
wherein the light-emitting part has a quadrangular shape, and at
least one side of the quadrangular shape is 100 .mu.m to 10000
.mu.m.
4. The biological information detector according to claim 1,
wherein the light-receiving part has a quadrangular shape.
5. The biological information detector according to claim 1,
further comprising a protector arranged on the side of the
detection site of at least one of the light-receiving part and the
light-emitting part.
6. The biological information detector according to claim 1,
wherein the light-receiving part, the light-emitting part, and the
reflecting part are arranged on a single substrate.
7. The biological information detector according to claim 1,
wherein the light-emitting part emits light whose maximum value of
intensity is in a wavelength range from 425 nm to 625 nm.
8. The biological information detector according to claim 5,
wherein the protector has an optical filter which cuts a
predetermined wavelength.
9. The biological information detector according to claim 8,
wherein the optical filter is an infrared-cutting filter.
10. The biological information detector according to claim 1,
wherein at least a part of the reflecting part is formed in a
curved shape in plan view.
11. The biological information detector according to claim 1,
wherein an area of the reflecting part is larger than an area of
the light-emitting part in plan view.
12. The biological information detector according to claim 1,
wherein an area of the light-receiving part is larger than an area
of the light-emitting part in plan view.
13. The biological information detector according to claim 1,
wherein the light-emitting part is arranged above the reflecting
part.
14. The biological information detector according to claim 13,
wherein the reflecting part has a concave portion and a reflecting
member arranged on a bottom portion of the concave portion, and the
light-emitting part is arranged above the reflecting member.
15. The biological information detector according to claim 1,
wherein the reflectivity of the reflecting part is 80 to 90%.
16. The biological information detector according to claim 1,
further comprising an acceleration rate sensor.
17. A biological information measurement device comprising: the
biological information detector according to claim 1; and a
biological information measurement unit for measuring biological
information on the basis of signals generated in a first
light-receiving part and signals generated in a second
light-receiving part.
18. The biological information measurement device according to
claim 17, wherein the biological information is a pulse count.
19. The biological information measurement device according to
claim 17, further comprising a motherboard, wherein the biological
information detector and the motherboard are connected with a
flexible board.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent Ser. No. 12/973,313 filed on Dec. 20, 2010. This application
claims priority to Japanese Patent Application No. 2010-000451
filed on Jan. 5, 2010. The entire disclosures of U.S. patent Ser.
No. 12/973,313 and Japanese Patent Application No. 2010-000451 are
expressly incorporated by reference herein.
BACKGROUND
[0002] 1. Technological Field
[0003] The present invention relates to a biological information
detector, a biological information measurement device, and the
like.
[0004] 2. Background Technology
[0005] A biological information measurement device is used for
measuring, for example, human pulse count, oxygen concentration in
the blood, body temperature, heart rate, or other biological
information; an example of which biological information measurement
device including a pulsometer for measuring pulse count. A
pulsometer or other biological information measurement device also
may be incorporated in, or combined with, a timepiece, portable
telephone, pager, PC, or other electronic device. A biological
information measurement device has a biological information
detector for detecting biological information, and the biological
information detector includes a light-emitting part for emitting
light toward a detection site of a test subject (user), and a
light-receiving part for receiving light including the biological
information from the detection site.
[0006] Patent Citation 1 discloses a pulsometer (in the broad
sense, a biological information measurement device). Each of a
first light-receiving part and a second light-receiving part (e.g.,
photodiodes 32 and 33 in FIG. 4 of Patent Citation 1) of the pulse
measurement device is used for detecting a noise component (e.g.,
electrical current ic in FIG. 5 of Patent Citation 1) originating
in external light. In the pulse measurement device 1 of Patent
Citation 1, the electrical current ic of the photodiode 32 and the
electrical current of the photodiode 33 are cancelled out. In other
words, in the pulse measurement device 1 of Patent Citation 1, the
noise component originating in external light is removed, and the
accuracy of detecting of biological information is improved. [0007]
Patent Citation 1: International Patent Publication No. 99/12469 is
an example of related art.
SUMMARY
[0008] A biological information detector according to one aspect
includes a light-emitting part, a reflecting part, and a
light-receiving part. The light-emitting part is configured and
arranged to emit light directed at a detection site of a test
subject. The reflecting part is arranged at the periphery of the
light-emitting part. The light-receiving part is configured and
arranged to receive reflected light at the detection site including
biological information. The light-emitting part and the
light-receiving part are arranged not to overlap each other in plan
view. A distance between the detection site and the light-emitting
part is different from a distance between the detection site and
the light-receiving part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is an example of the configuration of the biological
information detector of the present embodiment;
[0010] FIG. 2 is an example of the intensity characteristics of
light emitted by the detecting light-emitting part;
[0011] FIG. 3 is an example of the sensitivity characteristics to
light received by the detecting light-receiving part;
[0012] FIG. 4 is another example of the configuration of the first
sensor unit;
[0013] FIGS. 5(A) to (C) are examples of the configuration of the
first detecting reflector;
[0014] FIGS. 6(A) and (B) are examples of the external appearance
of the first detecting reflector and the detecting light-emitting
part 14-1;
[0015] FIG. 7 is another example of the configuration of the
biological information detector of the present embodiment;
[0016] FIG. 8 is another example of the configuration of the
biological information detector of the present embodiment;
[0017] FIG. 9 is an example of the external appearance of the
detecting light-receiving part;
[0018] FIG. 10 is another example of the configuration of the
biological information detector of the present embodiment;
[0019] FIG. 11 is an example of the transmission characteristics of
light passing through a board coated with a light-transmitting
film;
[0020] FIG. 12 is an example of the external appearance of the
light-transmitting film;
[0021] FIGS. 13(A) and (B) are graphs for describing the
infrared-cutting filter;
[0022] FIG. 14 is an example of storage of the board;
[0023] FIG. 15 is a diagram for describing the placement positions
of the detecting reflector and the correcting reflector;
[0024] FIG. 16 is a graph of the relationship between the placement
position of the detecting reflector and the amount of light
received by the detecting light-receiving part;
[0025] FIGS. 17(A) and (B) are examples of the external appearance
of a biological information measurement device including a
biological information detector;
[0026] FIGS. 18(A) and (B) are diagrams for describing a composite
light-receiving device; and
[0027] FIG. 19 is an example of the configuration of the biological
information measurement device.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0028] The present embodiment is described below. The present
embodiment is not to be unduly construed as a limitation of the
specifics of the present invention as described in the claims.
Also, not all of the configurations described in the present
embodiment are necessary configuration elements of the present
invention.
1. Biological Information Detector
[0029] FIG. 1 is an example of the configuration of the biological
information detector of the present embodiment. As illustrated in
FIG. 1, the biological information detector includes a first sensor
unit (corresponding to the first sensor unit) and a correcting
sensor unit (corresponding to the second sensor unit). The first
sensor unit has a detecting light-emitting part 14-1 (corresponding
to the light-emitting part), a detecting light-receiving part 16-1
(corresponding to the first light-receiving part), and a detecting
reflector 18-1 (corresponding to the first reflecting part). The
correcting sensor unit has a correcting light-receiving part 16-2
(corresponding to the second light-receiving part), and a
correcting reflector 18-2 (corresponding to the second reflecting
part).
[0030] In FIG. 1, the detecting light-emitting part 14-1 emits
light R1 toward a detection site O. The detecting light-receiving
part 16-1 receives light R1' containing biological information
obtained by the light R1 (reflected light) emitted toward the
detection site O being reflected by the detection site O, and light
R3' (transmitted light: noise) containing first noise information
obtained from external light R3 being transmitted through a test
subject (e.g., user). The detecting reflector 18-1 reflects the
light R1' (reflected light) containing the biological information
from the detection site O and the light R3' (transmitted light)
containing the first noise information from inside the test
subject, and leads the light to the detecting light-receiving part
16-1. The detecting reflector 18-1 may have a reflecting surface on
a domed surface provided on an optical path between the detecting
light-emitting part 14-1 and the detecting light-receiving part
16-1. The first sensor unit is used for detecting composite
information including the biological information in the detection
site of the test subject and the first noise information
originating in the external light R3.
[0031] The correcting light-receiving part 16-2 receives the light
R3' (transmitted light: noise) containing second noise information
obtained from the external light R3 being transmitted through the
test subject. The correcting reflector 18-2 reflects the light R3'
containing the second noise information from inside the test
subject, and leads the light to the correcting light-receiving part
16-2. The correcting reflector 18-2 may have a reflecting surface
on a domed surface provided on an optical path between the
detection site O and the correcting light-receiving part 16-2. The
correcting sensor unit is used for detecting the second noise
information originating in the external light R3. The correcting
sensor unit does not necessarily require a light-emitting part such
as the detecting light-emitting part 14-1 of the first sensor
unit.
[0032] In the example in FIG. 1, the detection site O (e.g., a
blood vessel) is inside the test subject. The first light R1 enters
into the test subject, and is diffused or scattered in the
epidermis, dermis, and hypodermis. The first light R1 then reaches
the detection site O, and is reflected by the detection site O. The
light R1' reflected by the detection site O is diffused or
scattered by the hypodermis, dermis, and epidermis, and proceeds
toward the detecting reflector 18-1. The first light R1 is
partially absorbed by the blood vessel. Accordingly, the absorption
rate in the blood vessel changes due to an effect of the pulse, and
the amount of light R1' reflected by the detection site O also
changes. The biological information (e.g., the pulse count) thus is
reflected in the light R1' reflected by the detection site O.
[0033] On the other hand, the external light R3 (e.g., sunlight) is
diffused or scattered inside the test subject. The transmitted
light R3' transmitted through the test subject without reaching the
detection site O proceeds toward the detecting reflector 18-1 or
the correcting reflector 18-2. Accordingly, the biological
information (pulse count) is not reflected in the transmitted light
R3' transmitted through the test subject. The external light R3 is
also diffused or scattered inside the test subject, for example, in
locations where tendons, bones, or other obstructions are not
present, and noise information is therefore reflected in the
transmitted light R3' transmitted through the test subject.
[0034] In the example in FIG. 1, the first light R1 is reflected
also by an outer surface (skin surface) SA of the test subject. In
the case when the detection site O is inside the test subject, the
biological information (pulse count) is not reflected in the light
R1'' (directly reflected light) reflected by the outer surface SA
of the test subject. In the example in FIG. 1, the reflected light
R1'' (in the broad sense, noise) is prevented from reaching the
correcting light-receiving part 16-2.
[0035] The configuration example of the biological information
detector is not limited by FIG. 1, and the shape, or the like, of a
part (e.g., detecting reflector 18-1 or correcting reflector 18-2)
of the configuration example may be modified. The biological
information may also be blood oxygen saturation, body temperature,
heart rate, or the like, and the detection site may also be on the
outer surface SA of the test subject. In FIG. 1, the first light R1
is depicted as three lines, but the detecting light-emitting part
14-1 in fact emits a large number of lights in various directions.
The external light R3 is also depicted as two lights, but a large
number of external lights in fact enter into the test subject from
various directions, and a large number of transmitted lights R3
transmitted through the test subject in fact proceed toward the
biological information detector as a result.
[0036] In FIG. 1, the reflected light R1' (valid light) reflected
by the detection site O reaches the detecting light-receiving part
16-1 by way of the detecting reflector 18-1, but is suppressed from
reaching the correcting light-receiving part 16-2. Accordingly, the
detecting light-receiving part 16-1 efficiently receives the light
emitted by the detecting light-emitting part 14-1, but the
correcting light-receiving part 16-2 receives almost no light
emitted by the detecting light-emitting part 14-1. The external
light R3 has a wavelength of 700 [nm] to 1100 [nm] that is easily
transmitted through the so-called "biological window," and the
transmitted light R3' (in the broad sense, noise) transmitted
through the test subject reaches the detecting reflector 18-1 and
the correcting reflector 18-2. The correcting light-receiving part
16-2 thus is independent from the detecting light-receiving part
16-1, and can efficiently sense the second noise information
originating in the external light R3 transmitted through the test
subject. Here, the transmitted light R1' containing the first noise
information obtained from the external light R3 being transmitted
through the test subject also is received by the detecting
light-receiving part 16-1, but the biological information in the
detection site O can be efficiently detected upon correction or
cancellation of the first noise information by the second noise
information. The detecting accuracy (S/N ratio) of the biological
information detector is thereby improved. In the case when the
reflecting surface of the detecting reflector 18-1 is a domed
surface, the reflected light R1' reflected by the detection site O
is more easily condensed on the detecting light-receiving part
16-1, and the reflected light R1' can be made less likely to reach
the correcting light-receiving part 16-2 to that extent. In such
case, the detecting accuracy (S/N ratio) of the biological
information detector is further increased.
[0037] Patent Citation 1 discloses a configuration (photodiode 33)
corresponding to the correcting light-receiving part 16-2, but the
photodiode 33 barely receives light emitted by an LED 31. Patent
Citation I also does not disclose a configuration corresponding to
the correcting reflector 18-1. The photodiode 33 thus is not
independent of the photodiode 32, and is not capable of efficiently
detecting just the noise information originating in the external
light. In other words, increasing the efficiency of the photodiode
33 in FIG. 4 of Patent Citation 1 is not known to persons skilled
in the art at the time of filing.
[0038] For example, the detecting light-emitting part 14-1 is an
LED. For example, the maximum value (in the broad sense, peak
value) of intensity of light emitted by an LED is in a wavelength
range from 425 [nm] to 625 [nm]. For example, green light is
emitted. For example, the thickness of the detecting light-emitting
part 14-1 is 20 [.mu.m] to 1000 [.mu.m]. For example, the detecting
light-receiving part 16-1 is a photodiode, and generally can be
configured with a Si photodiode. For example, the thickness of the
detecting light-receiving part 16-1 is 20 [.mu.m] to 1000 [.mu.m].
For example, the maximum value (in the broad sense, peak value) of
sensitivity to light received by a Si photodiode is in a wavelength
range from 800 [nm] to 1000 [nm]. Preferably, the detecting
light-receiving part 16-1 is configured with a GaAsP photodiode,
and for example, the maximum value (in the broad sense, peak value)
of sensitivity to light received by a GaAsP photodiode is in a
wavelength range from 550 [nm] to 650 [nm]. A biological substance
(water or hemoglobin) easily transmits infrared radiation included
in a range of 700 [nm] to 1100 [nm], and a detecting
light-receiving part configured with a GaAsP photodiode is
therefore more capable of reducing the noise component originating
in the external light, for example, compared with a light-receiving
part 16-1 configured with a Si photodiode.
[0039] For example, the correcting light-receiving part 16-2 is a
photodiode. The second noise information contained in the light
received by the correcting light-receiving part 16-2 is preferably
equal to the first noise information contained in the light
received by the detecting light-receiving part 16-1, and therefore
the correcting light-receiving part 16-2 is preferably the same
photodiode as the detecting light-receiving part 16-1.
[0040] FIG. 2 illustrates an example of the intensity
characteristics of light emitted by the detecting light-emitting
part 14-1. In the example in FIG. 2, the maximum value of intensity
is indicated for light having a wavelength of 520 [nm], and the
intensity of light of other wavelengths is normalized by that
intensity. In the example in FIG. 2, the wavelength range of light
emitted by the detecting light-emitting part 14-1 is from 470 [nm]
to 600 [nm].
[0041] FIG. 3 illustrates an example of the sensitivity
characteristics to light received by the detecting light-receiving
part 16-1. In the example in FIG. 3, the maximum value of
sensitivity is indicated for light having a wavelength of 565 [nm],
and the sensitivity to light in other wavelengths is normalized by
that sensitivity. The maximum value of sensitivity to wavelength of
light received by the detecting light-receiving part 16-1
illustrated in FIG. 3 is within the wavelength range of light
emitted by the detecting light-emitting part 14-1 illustrated in
FIG. 2, but is not within the range of 700 [nm] to 1100 [nm]
referred to as the "biological window." In the example in FIG. 3,
the sensitivity to infrared radiation included in the range from
700 [nm] to 1100 [nm] is set to a relative sensitivity of 0.3 (30
[%]) or lower. The maximum value (e.g., 565 [nm]) of sensitivity to
wavelength of light received by the detecting light-receiving part
16-1 is preferably closer to the maximum value (520 [nm]) of the
intensity of the wavelength of light emitted by the light-emitting
part 14 from the 700 [nm] lower limit of the biological window.
[0042] FIG. 4 illustrates another example of the configuration of
the first sensor unit. As illustrated in FIG. 4, the first sensor
unit of the biological information detector may include a detecting
reflector 42-1 (corresponding to the third reflector) for
reflecting light. Identical reference numerals are assigned to
identical configurations with the above configuration example, and
the description of the correcting sensor unit is omitted. In the
following description, the detecting reflector 42-1 is referred to
as "first detecting reflector," and the detecting reflector 18-1 in
FIG. 1 is referred to as "second detecting reflector."
[0043] In the example in FIG. 4, the first sensor unit of the
biological information detector includes a detecting light-emitting
part 14-1, a first detecting reflector 42-1, a detecting
light-receiving part 16-1, and a second detecting reflector 18-1.
The detecting light-emitting part 14-1 emits a first light R1
toward the detection site O of the test subject (user), and a
second light R2 toward a different direction (the first detecting
reflector 42-1) than the detection site O. The first detecting
reflector 42-1 reflects the second light R2 and leads the light to
the detection site O. The detecting light-receiving part 16-1
receives lights R1' and R2' (reflected lights) containing the
biological information obtained from the first light R1 and the
second light R2 being reflected by the detection site O. The second
detecting reflector 18-1 reflects the lights R1' and R2' (reflected
lights) containing the biological information from the detection
site O and leads the lights to the detecting light-receiving part
16-1. By the presence of the first detecting reflector 42-1, the
second light R2 not directly reaching the detection site O of the
test subject (user) also reaches the detection site O. In other
words, the amount of light reaching the detection site O is
increased by way of the first detecting reflector 42-1.
Accordingly, the detecting accuracy (S/N ratio) of the biological
information detector is improved.
[0044] In the example in FIG. 4, the second light R2 enters into
the test subject, and the light R2' reflected by the detection site
O proceeds toward the second detecting reflector 18-1. The
biological information (pulse count) is reflected also in the light
R2' reflected by the detection site O. In the example in FIG. 4,
the first light R1 is partially reflected by the outer surface
(skin surface) SA of the test subject. In the case when the
detection site O is inside the test subject, the biological
information (pulse count) is not reflected in the light R1''
(directly reflected light) reflected by the outer surface SA of the
test subject. In the example in FIG. 4, the transmitted light R3'
transmitted through the test subject proceeds toward the same
direction as the reflected light R1''.
[0045] In the example in FIG. 4, the detecting light-emitting part
14-1 may have a first light-emitting surface 14-1A for emitting the
first light R1, opposed to the detection site O. The detecting
light-emitting part 14-1 may also have a second light-emitting
surface 14-1B for emitting the second light R2, being to the side
of the first light-emitting surface 14-1A. In this case, the first
detecting reflector 42-1 may have a wall part surrounding the
second light-emitting surface 14-1B, and this wall part may have a
first reflecting surface (corresponding to the reference numeral
42B indicated in FIGS. 5(A) to (C)) for reflecting the second light
R2 toward the detection site O. The second light R2 is not
necessarily emitted from the second light-emitting surface 14-1B.
The point is that the first reflecting surface (reference numeral
42B in FIGS. 5(A) to (C)) reflects the light (second light R2)
other than the light directly emitted toward the detection site O
from the detecting light-emitting part 14-1, and leads the light to
the detection site O.
[0046] The wall part of the first detecting reflector 42 may
further have a second reflecting surface (corresponding to the
reference numeral 42C indicated in FIGS. 5(A) to (C) for reflecting
light (invalid light: noise) not containing the biological
information, reflected by the outer surface of the test subject,
and thereby suppressing the light not including the biological
information from being input to the detecting light-receiving part
16-1. The second reflecting surface (42C) can reflect also the
transmitted light R3' and suppressing input to the detecting
light-receiving part 16-1. The configuration example of the first
sensor unit of the biological information detector is not limited
by FIG. 4, and the shape, or the like, of a part (e.g., first
detecting reflector 42-1) of the configuration example may be
modified.
[0047] FIGS. 5(A), (B), and (C) illustrate an example of the
configuration of the first detecting reflector 42-1 in FIG. 4. As
illustrated in FIG. 5(A), the first detecting reflector 42-1 may
have a support part 42A for supporting the detecting light-emitting
part 14-1, and an inner wall surface 42B and a top surface 42C of a
wall part surrounding the second light-emitting surface 42B of the
detecting light-emitting part 14-1. In FIGS. 5(A) to (C), the
detecting light-emitting part 14-1 is omitted. In the example in
FIG. 5(A), the first detecting reflector 42-1 can reflect the
second light R2 on the inner wall surface 42B to the detection site
O (see FIG. 4), and has a first reflecting surface on the inner
wall surface 42B. For example, the thickness of the support part
42A is 50 [.mu.m] to 1000 [.mu.m], and for example, the thickness
of the wall part (42C) is 100 [.mu.m] to 1000 [.mu.m].
[0048] In the example in FIG. 5(A), the inner wall surface 42B has
an inclined surface (42B) that is displaced toward the side of the
detection site O in a height direction (a direction perpendicular
to a first direction) while going away from the center of the first
detecting reflector 42 in a width direction (the first direction)
in sectional view. The inclined surface (42B) in FIG. 5(A) is
formed as an inclined plane, but may be formed as a curved surface
or other inclined surface. The inner wall surface 42B may be formed
as a plurality of inclined planes having different angles of
inclination, or may be formed as curved surfaces having a plurality
of curvatures. In the case when the inner wall surface 42B of the
first detecting reflector 42-1 has an inclined surface, the inner
wall surface 42B of the first detecting reflector 42-1 can reflect
the second light R2 toward the detection site O. In other words,
the inclined surface of the inner wall surface 42B of the first
detecting reflector 42-1 may be considered as a first reflecting
surface for increasing the directionality of the detecting
light-emitting part 14-1. In this case, the amount of light
reaching the detection site O is further increased. The top surface
42C in FIGS. 5(A) and (C) may be omitted, for example, as
illustrated in FIG. 5(B). In the case when the first detecting
reflector 42-1 has a top surface 42C, the light R1'' (directly
reflected light) reflected by the outer surface SA of the test
subject can be reflected to the detection site or the periphery
thereof, and the reflected light R1'' can be suppressed from
reaching the detecting light-receiving part 16-1 (see FIG. 4). In
short, the top surface 42C in FIGS. 5(A) and (C) can be considered
as a second reflecting surface for reflecting the directly
reflected light (in the broad sense, noise) that would reach the
second detecting reflector 18-1 and the detecting light-receiving
part 16-1, and reducing the noise. In FIGS. 5(A) to (C), the range
indicated by the reference numeral 42D functions as a mirror
surface.
[0049] In the example in FIG. 4, the first detecting reflector 42-1
may project toward the detection site O, for example, by a given
height (e.g., .DELTA.h1=50 [.mu.m] to 950 [.mu.m]) with reference
to the surface of the detecting light-emitting part 14-1 defining
the shortest distance from the outer surface SA of the test
subject. In other words, a gap (e.g.,
.DELTA.h2=.DELTA.h0-.DELTA.h1=200 [.mu.m] to 1200 [.mu.m]) between
the first detecting reflector 42-1 and the outer surface SA of the
test subject can be made smaller than a gap (e.g.,
.DELTA.h0=.DELTA.h1+.DELTA.h2) being between the detecting
light-emitting part 14-1 and the outer surface SA of the test
subject. Accordingly, the area of the reflecting surface (42B) of
the first detecting reflector 42-1 can be increased, for example,
by the presence of the protruding amount .DELTA.h1 from the
detecting light-emitting part 14-1, and the amount of light
reaching the detection site O can be increased. An optical path for
the light reflected on the detection site O to reach the second
detecting reflector 18-1 from the detection site O can be secured
by the presence of the gap .DELTA.h2 between the first detecting
reflector 42-1 and the outer surface SA of the test subject. In the
case when the first detecting reflector 42-1 has a second
reflecting surface (92C), the amounts of light (valid light)
containing the biological information and light (invalid light:
noise) not containing the biological information input to the
detecting light-receiving part 16-1 can be respectively adjusted by
adjusting .DELTA.h1 and .DELTA.h2, whereby the S/N can be further
improved.
[0050] FIGS. 6(A) and (B) illustrate an example of the external
appearance in plan view of the first detecting reflector 42-1 and
the detecting light-emitting part 14-1 in FIG. 4. In the example in
FIG. 6(A), the outer perimeter of the first detecting reflector
42-1 expresses a circle in plan view (e.g., on the side of the
detection site O in FIG. 4), and, for example, the diameter of the
circle is 200 [.mu.m] to 11000 [.mu.m]. In the example in FIG.
6(A), the wall part (42B) of the first detecting reflector 42-1
surrounds the detecting light-emitting part 14-1 (see FIGS. 4 and
5(A)). The outer perimeter of the first detecting reflector 42-1
expresses a quadrangular shape (in the narrow sense, a square
shape) in plan view, for example, as illustrated in FIG. 6(B). In
the example in FIGS. 6(A) and (B), the outer perimeter of the
detecting light-emitting part 14-1 expresses a quadrangular shape
(in the narrow sense, a square shape) in plan view (e.g., on the
side of the detection site O in FIG. 4), and, for example, one side
of the square shape is 100 [.mu.m] to 10000 [.mu.m]. The outer
perimeter of the detecting light-emitting part 14-1 may describe a
circular shape.
[0051] The first detecting reflector 42-1 itself is formed with
metal, and the top surface is mirror-finished to have a reflective
structure (in the narrow sense, a mirror-reflective structure). The
first detecting reflector 42-1 may be formed, for example, with
resin, and the top surface may be mirror-finished. Specifically,
for example, a metal undercoating of the first detecting reflector
42-1 is prepared, and then, for example, the top surface is plated.
Or, for example, a thermoplastic resin is filled into a mold (not
illustrated) of the first detecting reflector 42-1, and then, for
example, a metal film is vapor-deposited on the top surface.
[0052] In the example in FIGS. 6(A) and (B), the first detecting
reflector 42-1 is exposed in a region (a part of the support part
42A, and the inner wall surface 42B and top surface 42C of the wall
part) other than the region where the detecting light-emitting part
14-1 is directly supported, in plan view (e.g., on the side of the
detection site O in FIG. 4). This exposed region is indicated as
the mirror-surface part 42D in the example in FIG. 5(A). In the
example in FIG. 5(A), the dotted line indicating the mirror surface
part 42D is positioned on the inside of the first detecting
reflector 42-1, but the mirror surface part 42D in fact is formed
on the top surface of the first detecting reflector 42-1.
[0053] In the example in FIGS. 5(A), (B), and (C), the mirror
surface part 42D preferably has high reflectivity. For example, the
reflectivity of the mirror surface part 42D is 80% to 90% or
higher. The mirror surface part 42D may be formed only on the
inclined surface of the inner wall surface 42B. In the case when
the mirror surface 42D is formed not only on the inclined surface,
but also on the support part 42A, the directionality of the
detecting light-emitting part 14 becomes even higher. In the case
when the mirror surface part 42D is formed on the top surface 42C,
the first detecting reflector 42-1 can reflect the light R1''
(directly reflected light: invalid light) reflected by the outer
surface SA of the test subject to the detection site O or the
periphery thereof, and the reflected light R1'' can be suppressed
from reaching the second detecting reflector 18-1 and the detecting
light-receiving part 16-1, for example, as illustrated in FIG. 4.
Because the directionality of the detecting light-emitting part
14-1 becomes higher, and because the directly reflected light (in
the broad sense, noise) is reduced, the detecting accuracy of the
biological information detector is improved.
[0054] In the example in FIG. 4, the transmitted light R3'
transmitted through the test subject proceeds in the same direction
as the reflected light R1''. That is, by the presence of the first
detecting reflector 42-1, the transmitted light R3' transmitted
through the test subject is suppressed from reaching the second
detecting reflector 18-1. Likewise, by the presence of the
detecting light-emitting part 14-1, the transmitted light R3'
transmitted through the test subject is suppressed from reaching
the second detecting reflector 18-1. For example, in the case when
the detecting light-emitting part 14-1 in FIG. 1 is as large as the
first detecting reflector 42-1 in FIG. 4, the transmitted light R3'
transmitted through the test subject is blocked or reflected by the
detecting light-emitting part 14-1, and is suppressed from reaching
the second detecting reflector 18-1. That is, the amount of
transmitted light R3' (external light) reaching the second
detecting reflector 18-1 is made less than the amount of
transmitted light R3' (external light) reaching the correcting
reflector, by the amount blocked or reflected by the detecting
light-emitting part or the first detecting reflector.
[0055] Then, in the example in FIG. 1, a relation S2<S1 may be
satisfied, for example, as in the example in FIG. 8, where S1 is
the area of the reflecting surface of the detecting reflector 18-1
(second detecting reflector 18-1 in FIGS. 4), and S2 is the area of
the reflecting surface of the correcting reflector 18-2. In the
case when the relation S2<S1 is satisfied, the transmitted light
R3' transmitted through the test subject can be suppressed from
reaching the correcting reflector 18-2, by the amount of reduction
of area (S1-S2) of the reflecting surface of the correcting
reflector 18-2. In other words, the amount of transmitted light R3'
(external light) reaching the correcting reflector 18-2 is reduced
by the amount of reduction of area (S1-S2) of the correcting
reflector 18-2. In the case when S1=S2, as previously described,
the amount of transmitted light R3' (external light) reaching the
second detecting reflector 18-1 becomes less than the amount of
transmitted light R3' (external light) reaching the correcting
reflector 18-2, and therefore the difference between the amount of
transmitted light R3' (external light) received by the correcting
light-receiving part 16-2 and the amount of transmitted light R3'
(external light) received by the detecting light-receiving part
16-1 can be reduced by reducing the amount of transmitted light R3'
(external light) reaching the correcting reflector 18-2.
[0056] FIG. 7 illustrates another example of the configuration of
the biological information detector of the present embodiment. As
illustrated in FIG. 7, the correcting sensor unit of the biological
information detector may have a dummy reflector 42-2 (corresponding
to the fourth reflector) for reflecting a part of the transmitted
light R3' (external light) transmitted through the test subject and
suppressing the transmitted light R3' from reaching the correcting
light-receiving part 16-2. Identical reference numerals are
assigned to identical configurations with the above-described
configuration example, and the description is omitted. The dummy
reflector 42-2 is referred to as "first correcting reflector," and
the correcting reflector 18-2 is referred to as "second correcting
reflector." In the example in FIG. 7, because the correcting sensor
unit does not have a light-emitting part such as the detecting
light-emitting part 14-1 of the first sensor unit, the dummy
reflector 42-2 (first correcting reflector) is originally not
required. However, by the presence of the dummy reflector 42-2
(first correcting reflector), a part of the transmitted light R3'
(external light) transmitted through the test subject is suppressed
from reaching the correcting reflector 18-2 (second correcting
reflector). In other words, even in the case when the area (S1) of
the reflecting surface of the detecting reflector 18-1 (second
detecting reflector) is equal to the area (S2) of the correcting
reflector 18-2 (second correcting reflector), the substantial area
(S2') of the reflecting surface of the correcting reflector 18-2
(second correcting reflector) is reduced by the presence of the
dummy reflector 42-2 (first correcting reflector). The difference
between the amount of transmitted light R3' (external light)
received by the correcting light-receiving part 16-2 and the amount
of transmitted light R3' (external light) received by the detecting
light-receiving part 16-1 can thus be reduced, or the difference
can be brought substantially to zero.
[0057] FIG. 8 illustrates another example of the configuration of
the biological information detector of the present embodiment. As
illustrated in FIG. 8, the biological information detector may
further include a substrate 81 having a first surface (e.g., top
surface) and a second surface (e.g., bottom surface) opposed to the
first surface. Identical reference numerals are assigned to
identical configurations with the above-described configuration
example, and the description is omitted. The detecting
light-receiving part 16-1 and the correcting light-receiving part
16-2 are disposed on the first surface, and the first detecting
reflector 42-1 is disposed on the second surface. A relation
W1.ltoreq.W2 may be satisfied, where W1 is the maximum length of
the first detecting reflector 42-1 in a direction parallel to the
first surface in sectional view, and W2 is the maximum length of
the detecting light-receiving part 16 in that direction.
[0058] For example, the substrate 81 is made of a transparent
material (e.g., polyimide), and transmits the reflected light R1'
of the first light R1 emitted to the detection site O. The amount
of light reaching the second detecting reflector 18-1 can be
increased by setting the maximum length W1 of the first detecting
reflector 42-1 to the maximum length W2 of the light-receiving part
16 or lower. In other words, the maximum length W1 of the first
detecting reflector 42-1 can be set so that the reflected light R1'
on the detection site O is not blocked or reflected by the first
detecting reflector 42-1. For example, the thickness of the
substrate 81 is 10 [.mu.m] to 1000 [.mu.m]. A wiring to the
detecting light-emitting part 14-1, a wiring to the detecting
light-receiving part 16-1, and a wiring to the correcting
light-receiving part 16-2 may be formed on the board. For example,
the substrate 81 is a printed board, but a printed board is not
usually made of a transparent material. In other words, the present
inventors ventured to constitute a printed board with a material
that is at least transparent to the wavelength of light emission of
the detecting light-emitting part 14-1.
[0059] In the example in FIG. 8, the second light R2 emitted by way
of the first detecting reflector 42-1, the reflected light R2' on
the detection site O, the light R1'' (directly reflected light)
reflected by the outer surface SA of the test subject, or the
transmitted light R3' transmitted through the test subject are
omitted (see FIG. 4). Persons skilled in the art should be able to
easily understand the path for the second light R2, the correct
path for the first light R1, or the correct path for the external
light R3.
[0060] As illustrated in FIG. 8, the biological information
detector may include a protector 89 for protecting the first
detecting reflector 42-1 and the detecting light-emitting part
14-1. For example, the protector 89 is made of a transparent
material (e.g., glass), and transmits the first light R1 emitted to
the detection site O and the reflected light R1' of the first light
R1. The protector 89 may ensure a gap (e.g., .DELTA.h2) is present
between the first detecting reflector 42-1 and the detection site
O. A gap (e.g., .DELTA.h2') between the first detecting reflector
42-1 and the protector 89 is also present. For example, the
thickness of the protector 89 is 1 [.mu.m] to 1000 [.mu.m].
[0061] The substrate 81 is held between a composite reflector
(second detecting reflector 18-1 and correcting reflector 18-2) and
the protector 89. The detecting light-receiving part 16-1 is placed
on the substrate 81 (in the narrow sense, on the first surface of
the substrate 81) on the side of the second detecting reflector
18-1. The detecting light-emitting part 14-1 is placed on the
substrate 81 (in the narrow sense, on the second surface of the
substrate 81) on the side of the protector 89. The correcting
light-receiving part 16-2 is placed on the substrate 81 (in the
narrow sense, on the first surface of the substrate 81) on the side
of the correcting reflector 18-2. Because the substrate 81 is held
between the composite reflector (second detecting reflector 18-1
and correcting reflector 18-2) and the protector 89, even though
the detecting light-emitting part 14-1, the detecting
light-receiving part 16-1, and the correcting light-receiving part
16-2 are disposed on the substrate 81, there is no need to
separately provide a mechanism for supporting the substrate 81
itself, and the number of parts is reduced. Because the substrate
81 is made of a material that is transparent to the wavelength of
light emission, the substrate 81 can be disposed partway along the
optical path from the detecting light-emitting part 14-1 to the
detecting light-receiving part 16-1, and there is no need to store
the substrate 81 in a position other than the optical path, for
example, inside the second detecting reflector 18-1. A biological
information detector that is easy to assemble can thus be
provided.
[0062] In the example in FIG. 8, a relation S2<S1 may be
satisfied, where S1 is the area of the reflecting surface of the
second detecting reflector 18-1, and S2 is the area of the
reflecting surface of the correcting reflector 18-2. By satisfying
the relation S2<S1, the transmitted light R3' transmitted
through the test subject is suppressed from reaching the correcting
reflector 18-2, by the amount of reduction of area (S1-S2) of the
reflecting surface of the correcting reflector 18-2. In the case
when S1=S2, the amount of transmitted light R3' (external light)
reaching the second detecting reflector 18-1 becomes less than the
amount of transmitted light R3' (external light) reaching the
correcting reflector 18-2, by the amount of transmitted light R3'
(external light) blocked by the first detecting reflector 42-1 and
the detecting light-emitting part 14-1. Therefore, the difference
between the amount of transmitted light R3' (external light)
received by the correcting light-receiving part 16-2 and the amount
of transmitted light R3' (external light) received by the detecting
light-receiving part 16-1 can be reduced by reducing the amount of
transmitted light R3' (external light) reaching the correcting
reflector 18-2.
[0063] FIG. 9 illustrates an example of the external appearance of
the detecting light-receiving part 16-1 in FIG. 8. In the example
in FIG. 9, the outer perimeter of the detecting light-receiving
part 16-1 expresses a quadrangular shape (in the narrow sense, a
square shape) in plan view (e.g., on the side of the second
detecting reflector 18-1 in FIG. 8), and for example, one side of
the square shape is 100 [.mu.m] to 10000 [.mu.m]. The outer
perimeter of the first detecting reflector 42-1 describes a circle
in plan view (e.g., on the side of the second detecting reflector
18-1 in FIG. 8). The outer perimeter of the first detecting
reflector 42-1 may describe a quadrangular shape (in the narrow
sense, a square shape) as in the example in FIG. 6(B). The outer
perimeter of the detecting light-receiving part 16-1 may describe a
circular shape.
[0064] In the example in FIG. 9, a relation W1.ltoreq.W2 may be
satisfied, where W1 is the maximum length of the first detecting
reflector 42-1, and W2 is the maximum length of the detecting
light-receiving part 16-1, as indicated by the line segment A-A'.
The sectional view along the line segment A-A' in FIG. 9
corresponds to FIG. 8. The sectional view along the line segment
B-B' in FIG. 9 is similar to FIG. 7, and the maximum length W1 of
the first detecting reflector 42-1 is longer than the minimum
length of the detecting light-receiving part 16-1. The maximum
length W1 of the first detecting reflector 42-1 may be set to the
minimum length of the detecting light-receiving part 16-1 or
shorter, but the efficiency of the first detecting reflector 42-1
(in the broad sense, the efficiency of the detecting light-emitting
part 14-1) is reduced. In the example in FIG. 9, the maximum length
W1 of the first detecting reflector 42-1 is set to maximum length
W2 of the detecting light-receiving part 16-1 or shorter, and the
maximum length W1 of the first detecting reflector 42-1 is set
larger than the minimum length of the detecting light-receiving
part 16-1, so that the reflected light R1' is not blocked or
reflected while the efficiency of the detecting light-emitting part
14-1 is maintained.
[0065] FIG. 10 illustrates another example of the configuration of
the biological information detector of the present embodiment. As
illustrated in FIG. 10, a light-transmitting film 81-1 may be
formed on the first surface (e.g., top surface) of the substrate
81, and on the second surface (e.g., bottom surface) opposed to the
first surface. Identical reference numerals are assigned to
identical configurations with the above-described configuration
example, and the description is omitted. The light-transmitting
film 81-1 may be formed only on the first surface or may be formed
only on the second surface. In the example in FIG. 10, the
light-transmitting film 81-1 is formed on a light-transmitting
region of the substrate 81 where the detecting light-emitting part
14-1 (in the narrow sense, the first detecting reflector 42-1), the
detecting light-receiving part 16-1, and the correcting
light-receiving part 16-2 are not disposed. For example, the
light-transmitting film 81-1 may be constituted with a solder
resist (in the broad sense, a resist). The detecting light-emitting
part (in the narrow sense, the first detecting reflector 42-1), the
detecting light-receiving part 16-1, the correcting light-receiving
part 16-2, and the like, may be disposed after the
light-transmitting film 81-1 is formed on the substrate 81. In the
example in FIG. 10, the second detecting reflector 18-1 and the
correcting reflector 18-2 are formed as a single composite
reflector.
[0066] In the example in FIG. 10, the wiring to the detecting
light-emitting part 14-1, the wiring to the detecting
light-receiving part 16-1, and the wiring to the correcting
light-receiving part 16-2 are omitted, but the first surface and
the second surface of the substrate 81 can be rough
surface-finished so that the wirings on the substrate 81 will not
detach. Accordingly, by forming the light-transmitting film 81-1 on
the first surface and the second surface, the rough surface on the
surface of the substrate 81 is embedded in the light-transmitting
film, and the overall flatness of the substrate 81 is improved. In
other words, because the light-transmitting film 81-1 on the
substrate 81 is flat, the diffusion of light on the rough surface
on the surface of the substrate 81 when the light is transmitted
through the substrate 81 can be reduced. In other words, the
transmittance of the substrate 81 is improved by the presence of
the light-transmitting film 81-1. Accordingly, the amount of light
reaching the detecting light-receiving part 16-1 and the correcting
light-receiving part 16-2 is increased, and the detecting accuracy
of the biological information detector is improved.
[0067] The refractive index of the light-transmitting film is
preferably between the refractive index of air and the refractive
index of the board. The refractive index of the light-transmitting
film 81-1 is preferably closer to the refractive index of the
substrate 81 than the refractive index of air. In such case, the
reflection of light at the interface can be reduced.
[0068] The biological information detector may further include an
infrared-cutting filter 89-1. An infrared-cutting filter 89-1 is
disposed on the optical path from the detecting light-emitting part
14-1 to the detecting light-receiving part 16-1. An
infrared-cutting filter 89-1 is likewise disposed also on the
optical path from the external light to the correcting
light-receiving part 16-2. In the example in FIG. 10, an
infrared-cutting filter 89-1 is formed on the contact surface of a
detection protector 89-1A and on the contact surface of a
correction protector 89-2A. In the example in FIG. 8, the contact
surface of the detection protector 89-1A, and the correction
protector 89-2A are formed as a single protector 89 (composite
protector). The infrared-cutting filter 89-1 in FIG. 10 may be
formed on the contact surface of the single protector 89. For
example, the infrared-cutting filter 89-1 may be constituted by
coating the contact surface of the detection protector 89-1A and
the contact surface of the correction protector 89-2A with an
infrared-absorbing material. In the case when the detection
protector 89-1A and the correction protector 89-2A (single
protector 89) are made of glass, the detection protector 89-1A and
the correction protector 89-2A (single protector 89) having the
infrared-cutting filter 89-1 may be referred to as
"infrared-cutting glass." The infrared-cutting filter 89-1 may be
formed on the entire surface on the outside of the detection
protector 89-1A and on the entire surface on the outside of the
correction protector 89-2A, rather than only on the contact surface
of the detection protector 89-1A and the contact surface of the
correction protector 89-2A. The infrared-cutting filter 89-1 may be
formed on the entire surface on the inside of the detection
protector 89-1A and on the entire surface on the inside of the
correction protector 89-2A. Or, the infrared-cutting filter 89-1
may be formed on the surface of the substrate 81, the detecting
light-receiving part 16-1 and on the surface of the correcting
light-receiving part 16-2, instead of on the contact surface of the
detection protector 89-1A and the contact surface of the correction
protector 89-2A. Because a biological substance (water or
hemoglobin) easily transmits infrared light, the noise component
originating in the external light can be reduced by an
infrared-cutting filter 89-1 disposed on the optical path from the
detecting light-emitting part 14-1 to the detecting light-receiving
part 16-1. In the correcting sensor unit, just as in the first
sensor unit, the noise component originating in the external light
can be reduced by disposing an infrared-cutting filter 89-1 on the
optical path from the external light to the correcting
light-receiving part 16-2.
[0069] FIG. 11 illustrates an example of the transmission
characteristics of light through a substrate 81 coated with a
light-transmitting film 81-1. In the example in FIG. 11, the
transmittance is calculated by using the intensity of the light
before transmission through the substrate 81 and the intensity of
the light after transmission through the substrate 81. In the
example in FIG. 11, the transmittance having a wavelength of 525
[nm] indicates the maximum value in the wavelength region at or
below 700 [nm], being the lower limit of the biological window. Or,
in the example in FIG. 11, the maximum value of transmittance of
the light transmitted through the light-transmitting film 81-1 in
the wavelength region at or below 700 [nm], being the biological
window, for example, enters a range of within .+-.10% of the
maximum value of the intensity of the wavelength of light emitted
by the detecting light-emitting part 14-1 in FIG. 2. Thus, the
light-transmitting film 81-1 is preferably one that selectively
transmits the light emitted by the detecting light-emitting part
14-1 (e.g., the first light R1 in FIG. 10 (in the narrow sense, the
reflected light R1' of the first light R1)). By the presence of the
light-transmitting film 81-1, the flatness of the substrate 81 is
improved, and a lowering of efficiency of the detecting
light-emitting part 14-1 or the detecting light-receiving part 16-1
can be prevented to a certain extent. As illustrated in the example
in FIG. 11, for example, in the case when the transmittance of the
light having a wavelength of 525 [nm] indicates the maximum value
(in the broad sense, peak value) in the visible light region, for
example, the light-transmitting film 81-1 expresses green
light.
[0070] FIG. 12 illustrates an example of the external appearance in
plan view of the light-transmitting film 81-1 in FIG. 10. As
illustrated in FIG. 12, the substrate 81 on which the
light-transmitting film 81-1 is formed expresses a rectangular
shape in plan view (e.g., on the side of the second detecting
light-receiving part 16-1 in FIG. 10). In the example in FIG. 12,
the detecting light-receiving part 16-1 and the correcting
light-receiving part 16-2 are placed on the first surface (e.g.,
top surface) of the substrate 81. The light-transmitting film 81-1
may be formed in a region of the first surface of the substrate 81
where the detecting light-receiving part 16-1 and the correcting
light-receiving part 16-2 are not placed.
[0071] Specifically, for example, a wiring 121 for connecting with
the anode of the detecting light-receiving part 16-1, and for
example, a wiring 122 for connecting with the cathode of the
detecting light-receiving part 16-1, are formed on the first
surface of the substrate 81. In the example in FIG. 12, for
example, the wiring 121 is connected with the anode of the
detecting light-receiving part 16-1 by way of a bonding wire 121-1,
and the wiring 122 is directly connected with the cathode of the
detecting light-receiving part 16-1. After the wiring 121 and the
wiring 122 are formed on the substrate 81, the light-transmitting
film 81-1 can be applied onto the first surface of the substrate
81. That is, the light-transmitting film 81-1 may be formed on top
of the wiring 121 and on the wiring 122. However, the
light-transmitting film may be applied selectively only in the
region of the substrate 81 where the detecting light-receiving part
16-1 as well as the wiring 121 and the wiring 122 are not
placed.
[0072] For example, a wiring 120 for connecting with the anode of
the correcting light-receiving part 16-2, and for example, a wiring
121 for connecting with the cathode of the correcting
light-receiving part 16-2, are formed on the first surface of the
substrate 81. For example, the wiring 120 is connected with the
anode of the correcting light-receiving part 16-2 by way of a
bonding wire 120-1, and the wiring 121 is directly connected with
the cathode of the correcting light-receiving part 16-2. The
cathode of the correcting light-receiving part 16-2 is connected
with the anode of the detecting light-receiving part 16-1 by way of
the wiring 121.
[0073] The composite reflector 18 can then be formed or fixed on
the substrate 81 (and the light-transmitting film 81-1). As
illustrated in FIG. 12, the external shape of the composite
reflector 18 describes a quadrangular shape. The external shape of
a boundary 18-1A between the reflecting surface (domed surface) of
the second detecting reflector 18-1 of the composite reflector 18
and the substrate 81 (light-transmitting film 81-1) describes a
circular shape. A boundary 18-2A between the reflecting surface
(domed surface) of the correcting reflector 18-2 of the composite
reflector 18 and the substrate 81 (light-transmitting film 81-1)
also expresses a circular shape. The light-transmitting film 81-1
may be applied selectively only in the light-transmitting regions
inside the boundary 18-1A (circular shape) and the boundary 18-2A
(circular shape). In other words, the light-transmitting film 81-1
may be applied selectively only in the light-transmitting regions
where the light received by the detecting light-receiving part 16-1
and the light received by the correcting light-receiving part 16-2
are transmitted.
[0074] In the example in FIG. 12, the detecting light-emitting part
14-1 and the first detecting reflector 42-1 are placed on the
second surface (e.g., bottom surface) of the substrate 81. Just as
with the first surface, the light-transmitting film 81-1 may be
formed in the region of the second surface of the substrate 81
where the detecting light-emitting part 14-1 and the first
detecting reflector 42-1 are not placed. The light-transmitting
film 81-1 is preferably formed at least in the light-transmitting
region (the light-transmitting region in which light emitted by the
detecting light-emitting part 14-1 and the external light are
transmitted). In the example in FIG. 12, a wiring 123 is formed on
the first surface on an end part 81-2 of the substrate 81, and is
formed on the second surface, passing through the substrate 81. A
second wiring 124 also is formed on the first surface on the end
part 81-2 of the substrate 81, and is formed on the second surface,
passing through the substrate 81. For example, the wiring 123 is
connected with the cathode of the detecting light-emitting part
14-1 on the second surface side by way of a bonding wire 123-1, and
a wiring 124 is connected with the cathode of the detecting
light-emitting part 14-1 on the second surface side by way of a
bonding wire 124-1. The wiring to the detecting light-emitting part
14-1, the detecting light-receiving part 16-1, and the correcting
light-receiving part 16-2 can be easily brought to the outside, by
arranging the end part 81-2 of the substrate 81 held between the
composite reflector 18 and the protector 89 to protrude to the
outside.
[0075] In the example in FIG. 12, a pseudo-wiring 125 is formed on
the second surface (e.g., bottom surface) of the substrate 81. By
the presence of the pseudo-wiring 125, a part of the transmitted
light R3' (external light) transmitted through the test subject is
suppressed from reaching the correcting reflector 18-2. The
difference between the amount of transmitted light R3' (external
light) received by the correcting light-receiving part 16-2 and the
amount of transmitted light R3' (external light) received by the
detecting light-receiving part 16-1 can thus be reduced.
[0076] FIGS. 13(A) and (B) illustrate graphs for describing the
infrared-cutting filter 89-1 in FIG. 10. FIG. 13(A) illustrates one
example of the transmission characteristics of light passing
through the protector 89 without the infrared-cutting filter 89-1.
FIG. 13(B) illustrates one example of the transmission
characteristics of light passing through an infrared-absorbing
material constituting the infrared-cutting filter 89-1. Referring
to FIGS. 13(A) and (B), light (e.g., external light) in a range
from 700 [nm] to 1100 [nm], referred to as the "biological window,"
can be prevented from entering by the presence of the
infrared-cutting filter 89-1. The infrared-cutting filter 89-1 may
be used for preventing the entrance of only a part of the
wavelength (e.g., 700 [nm] to 800 [nm]) in the range from 700 [nm]
to 1100 [nm].
[0077] FIG. 14 illustrates an example of the substrate 81 being
accommodated. In the example in FIG. 14, the substrate 81 may be
made of a flexible board. Accordingly, the end part 81-2 of the
substrate 81 is bendable. As illustrated in FIG. 14, the substrate
81 can be connected to a motherboard (e.g., a main board
constituting a biological information measurement device, described
further below) 142 of a computer in a state having bent the end
part 81-2 of the substrate 81. In other words, a small-sized
biological information detector can be provided by bending the
substrate 81. In FIG. 14, the light-transmitting film 81-1 is
omitted. The detecting light-emitting part 14-1, the detecting
light-receiving part 16-1, and the correcting light-receiving part
16-2 also are omitted. The wiring to the detecting light-emitting
part 14-1, the wiring to the detecting light-receiving part 16-1,
and the wiring to the correcting light-receiving part 16-2 can be
formed on the substrate 81, for example, as illustrated in FIG. 12,
and the wiring can be connected between a control circuit of the
motherboard 142 and the detecting light-emitting part 14-1, the
detecting light-receiving part 16-1, and the correcting
light-receiving part 16-2, by way of a connector 144.
[0078] The substrate 81 is held between the composite reflector 18
and the protector 89, whereby the composite reflector 18 is fixed
to the substrate 81. The substrate 81 where the composite reflector
18 is fixed is locally unbendable, but the end part 81-2 of the
substrate 81 where the composite reflector 18 is not fixed is
bendable. Because the substrate 81 is held between the composite
reflector 18 and the protector 89, the detecting light-emitting
part 14-1, the detecting light-receiving part 16-1, and the
correcting light-receiving part 16-2 can be mounted and supported
on the substrate 81 even though the substrate 81 itself is a
flexible board lacking rigidity.
[0079] FIG. 15 is a diagram for describing the placement positions
of the detecting reflector 18-1 and the correcting reflector 18-2
in FIG. 1, and the like. In FIG. 15, the detecting light-emitting
part 14-1, and the like, in FIG. 1, and the like, are omitted. For
example, the reflecting surface of the detecting reflector 18-1
(second detecting reflector 18-1) may be constituted as a spherical
surface (in the broad sense, domed surface) so that the reflected
light R1' of the first light R1 on the detection site O is
reflected to the detecting light-receiving part 16-1. As
illustrated in FIG. 15, the reflecting surface of the detecting
reflector 18-1 (second detecting reflector 18-1) expresses an arc
in sectional view. For example, the radius of the arc is 1000
[.mu.m] to 15000 [.mu.m]. The center C of the arc defining the
spherical surface is disposed inside the test subject. In the case
when there is a detection site O inside the test subject, the light
R1'' (directly reflected light) reflected by the outer surface SA
of the test subject is invalid light not including the biological
information. The present inventors recognized that, in the case
when the reflecting surface of the detecting reflector 18-1 (second
detecting reflector 18-1) is constituted as a spherical surface and
the center C of the arc defining the spherical surface is set
inside the test subject, the light (in the broad sense, noise)
reflected by the outer surface SA of the test subject is suppressed
by the detecting reflector 18-1 (second detecting reflector 18-1).
In FIG. 15, the distance between the light-receiving surface of the
detecting light-receiving part 16-1 and the center C of the arc
defining the spherical surface is indicated as .DELTA.h.
[0080] The reflecting surface of the detecting reflector 18-1
(second detecting reflector 18-1) may be constituted as a parabolic
surface (in the broad sense, domed surface) instead of a spherical
surface. As illustrated in FIG. 15, the reflecting surface of the
detecting reflector 18-1 (second detecting reflector 18-1)
describes an arc in sectional view, but may describe a parabola
instead of an arc. In FIG. 15, assuming that the reflecting surface
of the detecting reflector 18-1 (second detecting reflector 18-1)
is a parabolic surface, the focus of the parabola defining the
parabolic surface is indicated by the reference numeral F. The
focus F of the parabola defining the parabolic surface is disposed
toward the side of the test subject, with reference to the
light-receiving surface of the detecting light-receiving part 16-1.
Because the light perpendicular to the outer surface SA of the test
subject is reflected by the reflecting surface (parabolic surface)
of the detecting reflector 18-1 (second detecting reflector 18-1),
and is resolved on the focus F of the parabola defining the
parabolic surface, the light (e.g., the reflected light R1' (valid
light) of the first light R1) close to the light perpendicular to
the outer surface SA of the test subject is more easily condensed
by arranging the focus F so as not to coincide with the
light-receiving surface of the detecting light-receiving part
16-1.
[0081] The reflecting surface of the correcting reflector 18-2 may
be formed, for example, as a domed surface (spherical surface or
parabolic surface), just as the detecting reflector 18-1 (second
detecting reflector 18-1). As illustrated in FIG. 15, the
reflecting surface of the correcting reflector 18-2 describes an
arc in sectional view, but may describe a parabola. In the case
when the reflecting surface of the correcting reflector 18-2
describes an arc in sectional view, the radius of the arc of the
correcting reflector 18-2 may be set equal to the radius of the arc
of the detecting reflector 18-1 (second detecting reflector 18-1),
or may be set smaller than that radius. In FIG. 15, the distance
between the light-receiving surface of the correcting reflector
16-2 and the center C of the arc defining the spherical surface of
the correcting light-receiving part 16-2 is indicated by .DELTA.hc.
By satisfying the relation .DELTA.hc>.DELTA.h, the difference
between the amount of transmitted light R3' (external light)
received by the correcting light-receiving part 16-2 and the amount
of transmitted light R3' (external light) received by the detecting
reflector 18-1 (second detecting reflector 18-1) can be reduced. In
other words, by satisfying the relation .DELTA.hc>.DELTA.h, a
relation S2 (area of the reflecting surface of the correcting
reflector 18-2)<S1 (area of the reflecting surface of the
detecting reflector 18-1 (second detecting reflector 18-1)) may
also be satisfied. The relation S2<S1 may be satisfied by
setting the radius of the arc of the correcting reflector 18-2
smaller than the radius of the arc of the detecting reflector 18-1
(second detecting reflector 18-1).
[0082] In FIG. 15, assuming that the reflecting surface of the
correcting reflector 18-2 is a parabolic surface, the focus of the
parabola defining the parabolic surface is indicated by the
reference numeral F. The focus F of the parabola defining the
parabolic surface is disposed toward the side of the test subject,
with reference to the light-receiving surface of the correcting
light-receiving part 16-2. In the case when the reflecting surface
of the correcting reflector 18-2 describes a parabola in sectional
view, the focal distance of the parabola of the correcting
reflector 18-2 may be set equal to the focal distance of the
parabola of the detecting reflector 18-1 (second detecting
reflector 18-1), or may be set smaller than that focal distance. In
FIG. 15, the distance between the light-receiving surface of the
correcting reflector 16-2 and the focus F of the parabola defining
the parabolic surface of the correcting light-receiving part 16-2
is indicated by .DELTA.hc.
[0083] For example, the detecting reflector 18-1 (second detecting
reflector 18-1) is made of resin, and the top surface (the
reflecting surface on the side of the detecting light-receiving
part 16-1) is mirror-finished to have a reflective structure (in
the narrow sense, a mirror-reflective structure). In other words,
the detecting reflector 18-1 (second detecting reflector 18-1) may
be rendered to mirror-reflect light and not to diffusely reflecting
the light. In the case when the detecting reflector 18-1 (second
detecting reflector 18-1) has a mirror-reflective structure, this
detecting reflector 18-1 (second detecting reflector 18-1) can
prevent reflection of the reflected light R1'' (directly reflected
light) of the first light R1, having a different angle of
reflection from the angle of reflection of the reflected light R1'
of the first light R1, to the detecting light-receiving part 16-1.
In such a case, the detecting accuracy of the biological
information detector is further improved. As illustrated in FIG.
15, because the origin of the reflected light R1' of the first
light R1 is the detection site O inside the test subject, the angle
of reflection of the reflected light R1' of the first light R1 is
generally small. On the other hand, because the origin of the
reflected light R1'' of the first light R1 is the outer surface SA
of the test subject, the angle of reflection of the reflected light
R1'' of the first light R1 is generally large. For example, the
correcting reflector 18-2 also may be made of resin, and the top
surface (the reflecting surface on the side of the correcting
light-receiving part 16-2) may be mirror-finished to have a
reflective structure (in the narrow sense, a mirror-reflective
structure).
[0084] FIG. 16 is a graph of the relationship between the placement
position of the detecting reflector 18-1 in FIG. 15 and the amount
of light received by the detecting light-receiving part 16-1. As
illustrated in FIG. 16, as the distance .DELTA.h between the
light-receiving surface of the detecting light-receiving part 16-1
and the center C of the arc defining the spherical surface becomes
greater, the light (in the broad sense, noise, for example,
corresponding to the reflected light R1'') directly reflected by
the outer surface SA of the test subject decreases, and the light
(in the broad sense, biological information, for example,
corresponding to the reflected light R1') increases and then
decreases. The position of .DELTA.h can therefore be optimized. In
the case when the reflecting surface of the detecting reflector
18-1 (second detecting reflector 18-1) is a parabolic surface, the
distance between the light-receiving surface of the detecting
light-receiving part 16-1 and the focus F of the parabola defining
the parabolic surface also can be optimized.
2. Biological Information Measurement Device
[0085] FIGS. 17(A) and (B) are examples of the external appearance
of a biological information measurement device including the
biological information detector in FIG. 1, and the like. As
illustrated in FIG. 17(A), for example, the biological information
detector in FIG. 1 may further include a wristband 170 attachable
to an arm (in the narrow sense, wrist) of the test subject (user)
of the biological information detector. In the example in FIG.
17(A), the biological information is a pulse count, for example, as
indicated by "72." The biological information detector is
incorporated in a wristwatch, and the time (e.g., 8:15 a.m.) is
displayed. As illustrated in FIG. 17(B), two openings are provided
on the back cover of the wristwatch, and for example, the detection
protector 89-1 in FIG. 10 is exposed in one of the two openings.
For example, the correction protector 89-2A is exposed in the other
of the two openings. One opening may be provided on the back cover
of the wristwatch, and for example, the single protector 89
(composite protector) in FIG. 18 may be exposed in that opening. In
the example in FIG. 17(B), the second detecting reflector 18-1
(detecting reflector 18-1) and the detecting light-receiving part
16-1 are incorporated in the wristwatch, and the boundary 18-1A
between the reflecting surface (domed surface) of the second
detecting reflector 18-1 and the substrate 81 is depicted by a
dotted line. The correcting reflector 18-2 and the correcting
light-receiving part 16-2 also are incorporated in the wristwatch,
and the boundary 18-2A between the reflecting surface (domed
surface) of the correcting reflector 18-2 and the substrate 81 is
depicted by a dotted line. In the example in FIG. 17(B), the first
detecting reflector 42-1, the detecting light-emitting part 14-1,
and the like, are omitted.
[0086] In the example in FIG. 17(B), the detecting light-receiving
part 16-1 (in the broad sense, first sensor unit) and the
correcting light-receiving part (in the broad sense, correcting
sensor unit) are disposed along the direction of extension of the
wristband 170. The external light R3 enters between the wristband
170 and the arm from the surface side of the arm (the side of the
wrist on the side where the biological information detector is
worn). As illustrated in FIG. 17(A), the external light R3 enters,
for example, from the direction from the peripheral side (e.g., the
side of the back of the hand) toward the central side (shoulder
joint) in plan view. The transmitted light R3' transmitted through
the test subject proceeds toward the detecting light-receiving part
16-1 and the correcting light-receiving part 16-2. Accordingly, the
detecting light-receiving part 16-1 and the correcting
light-receiving part 16-2 may be disposed along the direction of
extension of the wristband 170, so that the transmitted light R3'
(external light R3) equally enters both the correcting sensor unit
and the first sensor unit.
[0087] FIGS. 18(A) and (B) are diagrams for illustrating a
composite light-receiving device. As illustrated in FIG. 1, and the
like, the biological information detector has a detecting
light-receiving part 16-1 and a correcting light-receiving part
16-2. As illustrated in FIG. 18(A), the anode of the detecting
light-receiving part 16-1 is connected with the cathode of the
correcting light-receiving part 16-2, and a composite
light-receiving part 16 is formed. However, the anode of the
detecting light-receiving part 16-1 may be made independent of the
cathode of the correcting light-receiving part 16-2, and the signal
(detecting light reception signal) generated in the detecting
light-receiving part 16-1 may be extracted independently from the
signal (correcting light reception signal) generated in the
correcting light-receiving part 16-2.
[0088] In the example in FIG. 18(A), the composite light-receiving
part 16 outputs a light reception signal expressing a difference
between the detecting light reception signal and the correcting
light reception signal. Because the detecting light reception
signal generated in the detecting light-receiving part 16-1
contains biological information originating in the light emitted
from the detecting light-emitting part 14-1 and noise information
originating in the external light, and the correcting light
reception signal generated in the correcting light-receiving part
16-2 contains noise information originating in the external light,
the light reception signal expressing the difference between the
detecting light reception signal and the correcting light reception
signal can express only the biological information originating in
the light emitted by the detecting light-emitting part 14-1. In
other words, the composite biological information (the biological
information in the detection site O and the first noise information
originating in the external light R3) can be corrected by the noise
information (the second noise information originating in the
external light R3) from the correcting light-receiving part
16-2.
[0089] As illustrated in the example in FIG. 18, a bipolar
transistor (in the broad sense, amplifier 184) for inputting and
amplifying on the basis of light reception signals of the composite
light-receiving part 16 may be added. A resistor 186 may further be
added between the anode of the detecting light-receiving part 16-1
and the cathode of the detecting light-receiving part 16-1. The
amplifier 184 and the resistor 186 may be disposed, for example, as
in FIG. 18(B). In FIG. 18(B), the shape of the end part 81-2 of the
substrate 81 differs from the shape of the end part 81-2 in FIG.
12, and is narrowed down. As illustrated in FIG. 18(B), an unwanted
part of the end part 81-2 can be removed.
[0090] FIG. 19 illustrates an example of the configuration of the
biological information measurement device. The biological
information measurement device includes the biological information
detector in FIG. 1, and the like, and a biological information
measurement unit for measuring biological information from
detecting light reception signals generated in the detecting
light-receiving part 16-1 and correcting light reception signals
generated in the correcting light-receiving part 16-2. As
illustrated in FIG. 19, the biological information detector may
have a detecting light-emitting part 14-1, a composite
light-receiving part 16 (detecting light-receiving part 16-1 and
correcting light-receiving part 16-2), and a control circuit 191
for the detecting light-emitting part 14-1. The biological
information detector may further have an amplification circuit 192
for light-reception signals from the composite light-receiving part
16. The biological information measurement unit may have an A/D
conversion circuit 193 for A/D-converting light-reception signals
from the composite light-receiving part 16, and a pulse-counting
circuit 194 for counting a pulse count. The biological information
measurement unit may further have a display unit 195 for displaying
the pulse count.
[0091] The biological information detector may have an acceleration
rate sensor 196, and the biological information measurement unit
may further have an A/D conversion circuit 197 for A/D-converting
light-reception signals from the acceleration rate sensor 196, and
a digital signal processing circuit 198 for processing the digital
signals. The configuration example of the biological information
measurement device is not limited to that shown in FIG. 19. The
pulse-counting circuit 194 in FIG. 19 may be an MPU
(micro-processing unit), being an electronic device incorporated in
the biological information detector.
[0092] The control circuit 191 is used for driving the detecting
light-emitting part 14-1. For example, the control circuit 191 is a
constant-current circuit, and a given voltage (e.g., 6 [V]) is
supplied to the detecting light-emitting part 14-1 by way of a
protective resistor, and the current flowing to the detecting
light-emitting part 14-1 is kept to a given value (e.g., 2 [mA].
The control circuit 191 can be used for driving the detecting
light-emitting part 14-1 intermittently in order to reduce the
consumption of current. The control circuit 191 is formed, for
example, on the motherboard 142, and the wiring between the control
circuit 191 and the detecting light-emitting part 14 is formed, for
example, on the substrate 81 in FIG. 12.
[0093] The amplification circuit 192 in FIG. 19 can be used for
removing a DC component from the light-reception signals (current)
generated in the composite light-receiving part 16, extracting only
an AC component, amplifying the AC component, and generating AC
signals. In the amplification circuit 192, for example, the DC
component at or below a given frequency is removed by a high-pass
filter, and for example, the AC component is buffered by an op-amp.
The light-reception signals include a pulse movement component and
a body movement component. The amplification circuit 192 or the
control circuit 191 can be used for supplying power current to the
composite light-receiving part 16 in order to operate with reverse
bias. In the case when the detecting light-emitting part 14 is
driven intermittently, the power to the composite light-receiving
part 16 also is supplied intermittently, and the AC component also
is amplified intermittently. The amplification circuit 192 is
formed, for example, on the motherboard 142, and the wiring between
the amplification circuit 192 and the composite light-receiving
part 16 is formed, for example, on the substrate 81 in FIG. 12. The
amplification circuit 192 may also have an amplifier 184 for
amplifying light-reception signals at the front end of the
high-pass filter. In the case when the amplification circuit 192
has an amplifier 184, the amplifier 184 is formed, for example, on
the substrate 81 in FIG. 18.
[0094] The A/D conversion circuit 193 in FIG. 19 is used for
converting AC signals generated in the amplification circuit 192 to
digital signals (first digital signals). The acceleration rate
sensor 196 is used for detecting the weight acceleration rate, for
example, on three axes (X, Y, and Z axes), and to generate
acceleration rate signals. Movement of the body (arm), and
accordingly movement of the biological information measurement
device, is reflected in the acceleration rate signals. The A/D
conversion circuit 197 in FIG. 19 is used for converting the
acceleration rate signals generated in the acceleration rate sensor
196 to digital signals (second digital signals).
[0095] The digital signal processing circuit 198 in FIG. 19 is used
for removing or reducing the body movement component in the first
digital signals using the second digital signals. For example, the
digital signal processing circuit 198 can be configured with a FIR
filter or other adaptive filter. In the digital signal processing
circuit 198, the first digital signals and the second digital
signals are input to the adaptive filter, and filter output signals
having removed or reduced noise are generated.
[0096] The pulse-counting circuit 194 in FIG. 19 is used for
performing a frequency analysis of the filter output signals, for
example, by fast Fourier transform (in the broad sense, discrete
Fourier transform). The pulse-counting circuit 194 is used for
identifying a frequency expressing the pulse component based on the
result of the frequency analysis, and for counting the pulse
count.
[0097] A biological information detector according to the
illustrated embodiment is characterized in comprising: a first
sensor unit for detecting composite information including
biological information of a detection site of a test subject and
first noise information originating in external light; and a second
sensor unit for detecting second noise information originating in
the external light; the first sensor unit having: a light-emitting
part for emitting a first light toward the detection site; a first
light-receiving part for receiving the light including the
biological information obtained from the first light emitted toward
the detection site being reflected by the detection site, and the
light including the first noise information obtained from the
external light being transmitted through the test subject; and a
first reflecting part for reflecting the light including the
biological information and the light including the first noise
information and leading the light to the first light-receiving
part; and the second sensor unit having: a second light-receiving
part for receiving the light including the second noise information
obtained from the external light being transmitted through the test
subject; and a second reflecting part for reflecting the light
including the second noise information and leading the light to the
second light-receiving part.
[0098] According to this aspect of the embodiment, the light
emitted by the light-emitting part is reflected by the detection
site, and is then reflected also by the first reflecting part. In
other words, the light reflected by the detection site reaches the
first light-receiving part by way of the first reflecting part, but
is suppressed from reaching the second light-receiving part.
Accordingly, the first light-receiving part efficiently receives
the light emitted by a first light-emitting part, but the second
light-receiving part receives almost no light emitted by the first
light-emitting part. The second light-receiving part thus is
independent from the first light-receiving part, and can
efficiently sense the second noise information originating in the
external light transmitted through the test subject. Here, the
light including the first noise information obtained from the
external light being transmitted through the test subject also is
received by the first light-receiving part, but the biological
information in the detection site can be efficiently detected upon
correction or cancellation of the first noise information by the
second noise information. The detecting accuracy (S/N ratio) of the
biological information detector is thereby improved.
[0099] According to a second aspect of the embodiment, a relation
S2<SI may be satisfied, where S1 is an area of a reflecting
surface of the first reflecting part, and S2 is an area of a
reflecting surface of the second reflecting part.
[0100] Because the first sensor unit has a light-emitting part, a
part of the external light transmitted through the test subject is
blocked or reflected by the light-emitting part, and is suppressed
from reaching the first reflecting part. That is, the amount of
external light reaching the first reflecting part is made less than
the amount of external light reaching the second reflecting part,
by the amount blocked or reflected by the light-emitting part.
Therefore, by satisfying the relation S2<S1, the amount of
external light transmitted through the test subject is suppressed
from reaching the second reflecting part, by the amount of
reduction of area (S1-S2) of the reflecting surface of the second
reflecting part. The difference between the amount of external
light received by the second light-receiving part and the amount of
external light received by the first light-receiving part can thus
be reduced. The first noise information detected by the first
sensor unit and the second noise information detected by the second
sensor unit can thereby be more accurately corrected or cancelled,
and the detecting accuracy of the biological information detector
is further improved.
[0101] According to a third aspect of the embodiment: the
light-emitting part may further emit a second light toward a
different direction from the detection site; the first sensor unit
may further have a third reflector for reflecting the second light
and leading the light to the detection site; and the first
light-receiving part may receive the light including the biological
information obtained from the second light being reflected by the
detection site.
[0102] Thus, by the presence of the third reflector, the second
light not directly reaching the detection site of the test subject
(e.g., user) also reaches the detection site. In other words, the
amount of light reaching the detection site is increased by way of
the third reflector. Accordingly, the detecting accuracy of the
biological information detector is improved.
[0103] According to a fourth aspect of the embodiment, the second
sensor unit may further have a fourth reflector for reflecting a
part of the light including the second noise information and
suppressing the light including the second noise information from
reaching the second light-receiving part.
[0104] Because a first sensor unit has a light-emitting part (and a
third reflector), a part of the external light transmitted through
the test subject is blocked or reflected by the light-emitting part
(or the third reflector), and is suppressed from reaching the first
reflecting part. That is, the amount of external light reaching the
first reflecting part is made less than the amount of external
light reaching the second reflecting part, by the amount blocked or
reflected by the light-emitting part (or the third reflector).
Therefore, by the presence of the fourth reflector (dummy
reflector), the part of the external light transmitted through the
test subject is suppressed from reaching the second reflecting
part, by being blocked or reflected by the fourth reflector. The
difference between the amount of external light received by the
second light-receiving part and the amount of external light
received by the first light-receiving part can thus be reduced. The
first noise information detected by the first sensor unit and the
second noise information detected by the second sensor unit can
thereby be more accurately corrected or cancelled, whereby the
detecting accuracy of the biological information detector is
further improved.
[0105] According to a fifth aspect of the embodiment: the first
sensor unit may further have: a wiring to the light-emitting part;
and a wiring to the first light-receiving part; and the second
sensor unit may further have: a wiring to the second
light-receiving part; and a pseudo-wiring for suppressing the light
including the second noise information from reaching the second
light-receiving part.
[0106] Because the first sensor unit has a first wiring to the
light-emitting part, the amount of external light transmitted
through the test subject is blocked or reflected by the wiring to
the light-emitting part, and is suppressed from reaching the first
reflecting part. Specifically, the amount of external light
reaching the first reflecting part is made less than the amount of
external light reaching the second reflecting part, by the amount
blocked or reflected by the wiring to the light-emitting part.
Therefore, by the presence of the pseudo-wiring, the part of the
external light transmitted through the test subject is suppressed
from reaching the second reflecting part, by being blocked or
reflected by the pseudo-wiring. The difference between the amount
of external light received by the second light-receiving part and
the amount of external light received by the first light-receiving
part can thus be reduced. The first noise information detected by
the first sensor unit and the second noise information detected by
the second sensor unit can thereby be more accurately corrected or
cancelled, whereby the detecting accuracy of the biological
information detector is further improved.
[0107] According to a sixth aspect of the embodiment: the first
reflecting part may be formed as a spherical surface or a parabolic
surface; the second reflecting part may be formed as a spherical
surface or a parabolic surface; and a relation
.DELTA.hc>.DELTA.h may be satisfied, where Ah is a distance
between a light-receiving surface of the first light-receiving part
and a center of an arc defining the spherical surface of the first
reflecting part or a focus of a parabola defining the parabolic
surface of the first reflecting part, and Ahc is a distance between
a light-receiving surface of the second light-receiving part and a
center of an arc defining the spherical surface of the second
reflecting part or a focus of a parabola defining the parabolic
surface of the second reflecting part.
[0108] Thus, by satisfying the relation .DELTA.hc>.DELTA.h, the
difference between the amount of external light received by the
second light-receiving part and the amount of external light
received by the first light-receiving part can be reduced. The
first noise information detected by the first sensor unit and the
second noise information detected by the second sensor unit can be
more accurately corrected or cancelled, whereby the detecting
accuracy of the biological information detector is further
improved.
[0109] A seventh aspect of the embodiment relates to a biological
information measurement device, characterized in comprising: a
biological information detector described above; and a biological
information measurement unit for measuring the biological
information on the basis of signals generated in the first
light-receiving part and signals generated in the second
light-receiving part.
[0110] According to an eighth aspect of the embodiment, the
measurement accuracy of the biological information measurement
device can be improved by using a biological information detector
having improved detecting accuracy.
[0111] According to a ninth aspect of the embodiment, the
biological information may be a pulse count.
[0112] A biological information measurement device having improved
measurement accuracy can thus be applied to a pulsometer.
[0113] Although a detailed description was made concerning the
present embodiment as stated above, persons skilled in the art
should be able to easily understand that various modifications are
possible without substantially departing from the scope and effects
of the present invention. Accordingly, all of such examples of
modifications are to be included in the scope of the present
invention. For example, terms stated at least once together with
different terms having broader sense or identical sense in the
specification or drawings may be replaced with those different
terms in any and all locations of the specification or
drawings.
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